- Achilles heel: In Greek mythology, the warrior Achilles was made invulnerable as a baby by being dipped into the River Styx. Only his heel—the place he was held by when being dipped—was left unprotected, which led to his downfall when it was struck by an arrow. An Achilles heel refers to a person's vulnerability or fatal flaw. He was a shrewd business man and investor, but his Achilles heel was gambling.
- Argus-eyed: According to the Greek legend, Argus had 100 eyes. The Greek queen Juno had him spy on her wayward husband, Zeus. Argus-eyed refers to jealous watchfulness. “Why so Argus-eyed, my love?” cried Bill. “I swear I've been at the office this whole time!”
- Bacchanalian: Bacchanalia was a Roman festival in honor of Bacchus, the god of wine (called Dionsyius in Greek mythology). The holiday was eventually banned due to drunken and libertine excess. Something described as Bacchanalian is similarly decadent and uninhibited. What started out as a genteel and subdued dinner party degenerated into Bacchanalian abandon as the hours wore on.
- Cupid: Cupid, or Amor, was the Roman god of love, who was also called Eros by the Greeks. He was usually depicted as a young winged boy with a bow and arrow. To play Cupid is to be a matchmaker, while someone who suddenly falls in love is said to have been struck by Cupid's arrow. Diane knew Sam had asked her not to get involved in his personal life, but she couldn't resist the urge to play Cupid and set him up with Rebecca.
- Gordian knot: According to Greek legend, King Gordius tied a wagon to a column with an extremely complex and intricate knot, which many tried and failed to undo. An oracle declared that whoever could untie the knot would rule the world. With a single stroke of his sword, Alexander the Great cut the knot in two, and went on to rule Asia. A Gordian knot is an intractable problem, and to cut the Gordian knot is to resolve a difficult problem with swift and bold action. The president believed he could cut through the Gordian knot of growing civil unrest by sending in the national guard with tear gas.
- Herculean: Hercules was a hero in Greek mythology who was renowned for his strength and courage. He is best known for completing his 12 labors, which included killing or capturing legendary creatures, gaining various items, and diverting a river to clean out the stables of Augeas. A Herculean feat is one very hard to perform, especially one requiring great strength. With a Herculean effort, Valjean lifted the cart off the man trapped underneath.
- Nemesis: Nemesis was a Greek goddess of retribution, the incarnation of the gods' revenge for violating their laws. As the gods' retribution could not be avoided, a nemesis is not only an agent of punishment, but any challenge or opponent that a person is unable to defeat. He used all his willpower to stay on the diet, but the doughnut shop next door proved to be his nemesis.
- Pandora's box: Pandora, according to Greek mythology, was the first woman on earth. Created by Zeus in revenge for Prometheus's stealing of fire, she was given a box that she was told not to open. Either she or her husband Epimetheus—tellings diverge on that point—opened the box, allowing all manner of evils to escape and plague the world. A Pandora's box is anything that, upon investigation, leads to extensive and unexpected troubles. The investigation of drug use among the athletes opened a Pandora's Box implicating half the league.
- Promethean: In Greek mythology, Prometheus defied Zeus, stealing fire from the heavens and giving it to the human race. His name has become associated with bold originality and creativity. Although religious authorities and moralists objected to the new procedure, the Promethean scientists would not be denied.
- Protean: Proteus was a Greek god who had the ability to change his shape. Someone or something that easily adapts to changing situations or roles by changing itself is described as protean. The senator's protean policies always mirrored the whims of his electorate.