Aegis    a shield used by Thalia Grace that has a fear-inducing image of Medusa on its front; it turns into a silver bracelet when she isn’t using it

Aethiopian Bull    a giant, aggressive African bull whose red hide is impervious to all metal weapons

Agamethus    son of King Erginus; half brother of Trophonius, who decapitated him to avoid discovery after their raid on King Hyrieus’s treasury

Amazon    a member of a tribe of warrior women

amphitheater    an oval or circular open-air space used for performances or sporting events, with spectator seating built in a semicircle around the stage

amphora    ceramic jar used to hold wine

Ares    the Greek god of war; the son of Zeus and Hera, and half brother to Athena

Artemis    the Greek goddess of the hunt and the moon; the daughter of Zeus and Leto, and the twin of Apollo

Asclepius    the god of medicine; son of Apollo; his temple was the healing center of ancient Greece

Athena    the Greek goddess of wisdom

Athenian    of the city of Athens, Greece

Atlas    a Titan; father of Calypso and Zoë Nightshade; he was condemned to hold up the sky for eternity after the war between the Titans and the Olympians; he tried unsuccessfully to trick Hercules into taking his place forever, but Hercules tricked him in return

blemmyae    a tribe of headless people with faces in their chests

Britomartis    the Greek goddess of hunting and fishing nets; her sacred animal is the griffin

Bruttia Crispina    a Roman Empress from 178 to 191 CE; she was married to future Roman Emperor Commodus when she was sixteen years old; after ten years of marriage, she was banished to Capri for adultery and later killed

Byzantium    an ancient Greek colony that later became Constantinople (now Istanbul)

caduceus    the traditional symbol of Hermes, featuring two snakes winding around an often winged staff

Calliope    the muse of epic poetry; mother of several sons, including Orpheus

Calypso    the goddess nymph of the mythical island of Ogygia; a daughter of the Titan Atlas; she detained the hero Odysseus for many years

Camp Half-Blood    the training ground for Greek demigods, located in Long Island, New York

Camp Jupiter    the training ground for Roman demigods, located between the Oakland Hills and the Berkeley Hills, in California

Carthaginian Serpent    a 120-foot snake that emerged from the River Bagrada in North Africa to confront Roman General Marcus Atilius Regulus and his troops during the First Punic War

Cave of Trophonius    a deep chasm, home to the Oracle of Trophonius

centaur    a race of creatures that is half-human, half-horse

centicore (see also yale)    a fierce yak-like creature with large horns that can swivel in any direction

Chiron    a centaur; the camp activities director at Camp Half-Blood

chiton    a Greek garment; a sleeveless piece of linen or wool secured at the shoulders by brooches and at the waist by a belt

Cloacina    goddess of the Roman sewer system

Colosseum    an elliptical amphitheater in the center of Rome, Italy, capable of seating fifty thousand spectators; used for gladiatorial contests and public spectacles; also called the Flavian Amphitheater

Colossus Neronis (Colossus of Nero)    a gigantic bronze statue of the Emperor Nero; was later transformed into the sun god with the addition of a sunray crown

Commodus    Lucius Aurelius Commodus was the son of Roman Emperor Marcus Aurelius; he became co-emperor when he was sixteen and emperor at eighteen, when his father died; he ruled from 177 to 192 CE and was megalomaniacal and corrupt; he considered himself the New Hercules and enjoyed killing animals and fighting gladiators at the Colosseum

Cretan    of the island of Crete

Cyclops (Cyclopes, pl.)    a member of a primordial race of giants, each with a single eye in the middle of his or her forehead

Daedalus    a skilled craftsman who created the Labyrinth on Crete in which the Minotaur (part man, part bull) was kept

daimon    Greek for demon; an intermediary spirit between mortals and the gods

Dambe    a centuries-old form of boxing associated with the Hausa people of West Africa

Danubian    bordering the Danube river in Europe

Daphne    a beautiful naiad who attracted Apollo’s attention; she was transformed into a laurel tree in order to escape him

Delos    a Greek island in the Aegean Sea near Mykonos; birthplace of Apollo

Demeter    the Greek goddess of agriculture; a daughter of the Titans Rhea and Kronos

Demophon    the baby son of King Celeus, whom Demeter nursed and tried to make immortal as an act of kindness; brother of Triptolemus

Dionysus    the Greek god of wine and revelry; the son of Zeus

Dionysus Festival    a celebration held in Athens, Greece, to honor the god Dionysus, the central events of which were theatrical performances

Doors of Death    the doorway to the House of Hades, located in Tartarus; doors have two sides—one in the mortal world, and one in the Underworld

elomìíràn    the Yoruba word for others

Elysium    the paradise to which Greek heroes were sent when the gods gave them immortality

Erythaea    an island where the Cumaean Sibyl, a love interest of Apollo, originally lived before he convinced her to leave it by promising her a long life

Eubouleus    son of Demeter and Karmanor; the Greek god of swineherds

Fields of Punishment    the section of the Underworld where people who were evil during their lives are sent to face eternal punishment for their crimes after death

Flavian    the Flavians were an imperial dynasty that ruled the Roman Empire between 69 and 96 CE

Gaea    the Greek earth goddess; wife of Ouranos; mother of Titans, giants, Cyclopes, and other monsters

Ganymede    a divine hero from Troy whom Zeus abducted to serve as his cupbearer in Olympus

Germani (Germanus, sing.)    tribal people who settled to the west of the Rhine river

Gidigbo    a form of wrestling that involves head-butting, from the Yoruba of Nigeria, Africa

gloutos    Greek for buttocks

Gorgons    three monstrous sisters (Stheno, Euryale, and Medusa) who have hair of living, venomous snakes; Medusa’s eyes can turn the beholder to stone

Greek fire    an incendiary weapon used in naval battles because it can continue burning in water

griffin    a winged creature with the head of an eagle and the body of a lion; the sacred animal of Britomartis

Grove of Dodona    the site of the oldest Greek Oracle, second only to Delphi in importance; the rustling of trees in the grove provided answers to priests and priestesses who journeyed to the site

Hades    the Greek god of death and riches; ruler of the Underworld

harpy    a winged female creature that snatches things

Hausa    a language spoken in northern Nigeria and Niger; also the name of a people

Hecate    goddess of magic and crossroads

Hemithea    teenage daughter of King Staphylus of Naxos; sister of Parthenos; Apollo made her and her sister divine to save them when they jumped off a cliff to escape their father’s rage

Hephaestus    the Greek god of fire and crafts and of blacksmiths; the son of Zeus and Hera, and married to Aphrodite

Hera    the Greek goddess of marriage; Zeus’s wife and sister; Apollo’s stepmother

Heracles    the Greek equivalent of Hercules; the son of Zeus and Alcmene; the strongest of all mortals

Hercules    the Roman equivalent of Heracles; the son of Jupiter and Alcmene, who was born with great strength

Hermes    Greek god of travelers; guide to spirits of the dead; god of communication

Hessian mercenaries    the approximately thirty thousand German troops hired by the British to help fight during the American Revolution when they found it too difficult to recruit their own soldiers

hippocampi (hippocampus, sing.)    half-horse, half-fish creatures

Hunters of Artemis    a group of maidens loyal to Artemis and gifted with hunting skills and eternal youth as long as they reject romance for life

Hyacinthus    a Greek hero and Apollo’s lover, who died while trying to impress Apollo with his discus skills

ichor    the golden fluid that is the blood of gods and immortals

ìgboyà    the Yoruba word for confidence, boldness, and bravery

Imperial gold    a rare metal deadly to monsters, consecrated at the Pantheon; its existence was a closely guarded secret of the emperors

Iris    the Greek goddess of the rainbow, and a messenger of the gods

Julius Caesar    a Roman politician and general who became a dictator of Rome, turning it from a republic into the Roman Empire

Karmanor    a minor Greek harvest god; a local deity in Crete who married Demeter; together they had a son, Eubouleus, who became the god of swineherds

karpoi (karpos, sing.)    grain spirits

Kronos    the youngest of the twelve Titans; the son of Ouranos and Gaea; the father of Zeus; he killed his father at his mother’s bidding; Titan lord of fate, harvest, justice, and time

Labyrinth    an underground maze originally built on the island of Crete by the craftsman Daedalus to hold the Minotaur

Lethe    the Greek word for forgetfulness; the name of a river in the Underworld whose waters caused forgetfulness; the name of a Greek spirit of oblivion

Leto    mother of Artemis and Apollo with Zeus; goddess of motherhood

Little Tiber    the barrier of Camp Jupiter

Lityerses    the son of King Midas; he challenged people to harvesting contests and beheaded those he beat, earning him the nickname “Reaper of Men”

Marcus Aurelius    Roman Emperor from 161 to 180 CE; father of Commodus; considered the last of the “Five Good Emperors”

Marsyas    a satyr who lost to Apollo after challenging him in a musical contest, which led to Marsyas being flayed alive

melomakarona    Greek Christmas honey cookies

Midas    a king with the power to transform anything he touched to gold; Lityerses’s father; he selected Marsyas as the winner in the musical contest between Apollo and Marsyas, resulting in Apollo giving Midas the ears of a donkey

Minotaur    the half-man, half-bull son of King Minos of Crete; the Minotaur was kept in the Labyrinth, where he killed people who were sent in; he was finally defeated by Theseus

Mnemosyne    Titan goddess of memory; daughter of Ouranos and Gaea

Mount Olympus    home of the Twelve Olympians

Mount Othrys    a mountain in central Greece; the Titans’ base during the ten-year war between the Titans and the Olympians

myrmeke    a large antlike creature that poisons and paralyzes its prey before eating it; known for protecting various metals, particularly gold

Narcissus    a hunter known for his beauty; the son of the river god Cephissus and the nymph Liriope; he was vain, arrogant, and disdainful of admirers; he fell in love with his own reflection; Narcissus was also the name of Commodus’s personal trainer and wrestling partner, who drowned the emperor in his bathtub—these were two different Narcissuses

Nemean Lion    a large, vicious lion that plagued Nemea in Greece; its pelt was impervious to all human weapons; Hercules strangled it with his bare hands

Nero    ruled as Roman Emperor from 54 to 58 CE; he had his mother and his first wife put to death; many believe he was responsible for setting a fire that gutted Rome, but he blamed the Christians, whom he burned on crosses; he built an extravagant new palace on the cleared land and lost support when construction expenses forced him to raise taxes; he committed suicide

Nine Muses    Greek goddesses of literature, science, and the arts, who have inspired artists and writers for centuries

nymph    a female nature deity who animates nature

Oceanus    the eldest son of Ouranos and Gaea; the Titan god of the sea

Ogygia    the island home—and prison—of the nymph Calypso

Oracle of Delphi    a speaker of the prophecies of Apollo

Oracle of Trophonius    a Greek who was transformed into an Oracle after his death; located at the Cave of Trophonius; known for terrifying those who seek him

Orion    a giant huntsman who was the most loyal and valued of Artemis’s attendants until he was slain by a scorpion

Ouranos    the Greek personification of the sky; husband of Gaea; father of the Titans

Pan    the Greek god of the wild; the son of Hermes

Parthenos    teenage daughter of King Staphylus of Naxos; sister of Hemithea; Apollo made her and her sister divine to save them when they jumped off a cliff to escape their father’s rage

Peloponnese    a large peninsula and geographic region in southern Greece, separated from the northern part of the country by the Gulf of Corinth

Persephone    the Greek queen of the Underworld; wife of Hades; daughter of Zeus and Demeter

podex    Latin for anus

Poseidon    the Greek god of the sea; son of the Titans Kronos and Rhea, and brother of Zeus and Hades

Potina    a Roman goddess of children, who watches over what they are drinking

praetor    an elected Roman magistrate and commander of the army

Primordial Chaos    the first thing ever to exist; the miasma from which the Fates wove the future; a void from which the first gods were produced

princeps    prince of Rome; the early emperors used this title for themselves

Python    a monstrous serpent that Gaea appointed to guard the Oracle at Delphi

River Styx    the river that forms the boundary between earth and the Underworld

satyr    a Greek forest god, part goat and part man

Sibyl    a prophetess

Sibylline Books    a collection of prophecies in rhyme written in Greek

Sparta    a city-state in ancient Greece with military dominance

spatha    a long sword used by Roman cavalry units

Staphylus    king of Naxos, Greece; a demigod son of Dionysus; father of Hemithea and Parthenos

Styx    a powerful water nymph; the eldest daughter of the sea Titan, Oceanus; goddess of the Underworld’s most important river; goddess of hatred; the River Styx is named after her

Suburra    an area of the city of Rome that was crowded and lower-class

Tantalus    a king who fed the gods a stew made of his own son; he was sent to the Underworld, where his curse was to be stuck in a pool of water under a fruit tree but never be able to drink or eat

Tartarus    husband of Gaea; spirit of the abyss; father of the giants; the lowest part of the Underworld

Teumessian Fox    a giant fox sent by the gods to ravage the city of Thebes in punishment for a crime; the beast was destined never to be caught

Three Fates    Even before there were gods there were the Fates: Clotho, who spins the thread of life; Lachesis, the measurer, who determines how long a life will be; and Atropos, who cuts the thread of life with her shears

Three Mile Island    a nuclear power plant near Harrisburg, Pennsylvania, where, on March 28, 1979, there was a partial meltdown in reactor number 2, causing public concern

Throne of Memory    Mnemosyne carved this chair, in which a petitioner would sit after visiting the Cave of Trophonius and receiving bits of verse from the Oracle; once seated in the chair, the petitioner would recount the verses, the priests would write them down, and they would become a prophecy

Tiber River    the third-longest river in Italy; Rome was founded on its banks; in ancient Rome, executed criminals were thrown into the river

Titan War    the epic ten-year battle between the Titans and the Olympians that resulted in the Olympians taking the throne

Titans    a race of powerful Greek deities, descendants of Gaea and Ouranos, that ruled during the Golden Age and were overthrown by a race of younger gods, the Olympians

Triptolemus    son of King Celeus and brother of Demophon; a favorite of Demeter; he became the inventor of the plow and agriculture

trireme    a Greek warship, having three tiers of oars on each side

triumvirate    a political alliance formed by three parties

Trojan War    According to legend, the Trojan War was waged against the city of Troy by the Achaeans (Greeks) after Paris of Troy took Helen from her husband, Menelaus, king of Sparta

Trophonius    demigod son of Apollo, designer of Apollo’s temple at Delphi, and spirit of the dark Oracle; he decapitated his half brother Agamethus to avoid discovery after their raid on King Hyrieus’s treasury

Troy    a Roman city situated in modern-day Turkey; site of the Trojan War

Underworld    the kingdom of the dead, where souls go for eternity; ruled by Hades

Via Appia    the Appian Way, one of the first and most important roads of the ancient Roman republic; after the Roman army subdued the revolt led by Spartacus in 73 BC, they crucified more than six thousand slaves and lined the road for 130 miles with their bodies

yale    (see also centicore) a fierce yak-like creature with large horns that can swivel in any direction

Yoruba    one of the three largest ethnic groups in Nigeria, Africa; also a language and a religion of the Yoruba people

Zeus    the Greek god of the sky and the king of the gods

Zoë Nightshade    a daughter of Atlas who was exiled and later joined the Hunters of Artemis, becoming the loyal lieutenant of Artemis