Trojan horse, Nemesis, Myrmidon, Draconian... - definitions from Ninjawords (a really fast dictionary)

Trojan horse: noun; °(Greek legend) a hollow wooden horse by which the Greeks gained access to Ilium or Troy.; °(by extension) a subversive person or device placed within the ranks of the enemy.

"Nemesis" is not in the dictionary.

Myrmidon: noun; °One of a fierce tribe or troop who accompanied Achilles, their king, to the Trojan war.

"Draconian" is not in the dictionary.

Cyclopean: adjective; °Suggestive of a Cyclops.; °Of a style of ancient masonry where walls are fitted together of huge irregular stones; ancient and roughly composed.

Cassandra: noun; °Daughter of King Priam of Troy and his queen Hecuba, who captured the eye of Apollo and was granted the ability to see the future. However, she was destined to never be believed.; °.

Arcadia: noun; °A district or a prefecture in the central and mid SE Peloponnese that has a population of more than 110,000. Tripoli is the capital and a main city with a population over 22,000.; °A mountainous region of ancient Greece.

Achilles' heel: noun; °alternative spelling of Achilles heel.