All 3 Uses

chimera
in
The Aeneid
(Auto-generated)

The speedy Dolphin, that outstrips the wind, Bore Mnestheus, author of the Memmian kind: Gyas the vast Chimaera's bulk commands, Which rising, like a tow'ring city stands; Three Trojans tug at ev'ry lab'ring oar; Three banks in three degrees the sailors bore; Beneath their sturdy strokes the billows roar.†
Book 5
Before the passage, horrid Hydra stands, And Briareus with all his hundred hands; Gorgons, Geryon with his triple frame; And vain Chimaera vomits empty flame.†
Book 6 *
Amid the troops, and like the leading god, High o'er the rest in arms the graceful Turnus rode: A triple of plumes his crest adorn'd, On which with belching flames Chimaera burn'd: The more the kindled combat rises high'r, The more with fury burns the blazing fire.†
Book 7

Definitions:

(1) (chimera)
a wild, unrealistic idea or hope; or a mythical creature made from parts of different animals
(2) (meaning too rare to warrant focus)
As a proper noun Chimera refers to a fire-breathing monster in Greek mythology. It is a female monster with a lion's head, a goat's body, and a serpent's tail.

More rarely, in biology, a chimera is an organism that contains cells or tissues with a different genotype.

Chimaera is also an acceptable spelling and the name of a type of fish.