(plural Cyclopes), in Greek mythology, a giant with one eye, circular and in the middle of the forehead, 1510s, from Latin Cyclops, from Greek kyklops, literally "round-eyed," from stem of kyklos "circle, circular body" (from PIE root *kwel- (1) "revolve, move round") + ops "eye" (from PIE root *okw- "to see").

According to the Hesiodic legend, there were three Cyclopes of the race of Titans, sons of Uranus and Ge, who forged the thunderbolts of Zeus, Pluto's helmet, and Poseidon's trident, and were considered the primeval patrons of all smiths. Their workshops were afterward said to be under Mount Etna. [Century Dictionary]

But in the Odyssey they were lawless gigantic cannibal shepherds in Sicily under their chief Polyphemus, and in other ancient tales they were race of giants from Thrace under a king Cyclops, who built the prehistoric walls and fortresses of Greece. Related: Cyclopic.

"circular panorama, picture of a landscape, battle, etc., arranged on the interior surface of a cylindrical room or other space," 1840, from cyclo- + -rama "spectacle." Related: Cycloramic.

"apparatus for accelerating charged atomic particles by causing them to revolve in orbits of increasing diameter," 1935, from cyclo- + ending from electron.

"a young swan," c. 1400, also signet before 17c., from Anglo-French cignet (mid-14c.), Anglo-Latin cygnettus, diminutives of Old French cigne, cisne "swan" (12c., Modern French cygne), from Latin cygnus, from Greek kyknos, which has been the subject of "abundant discussion" (Beekes) and is perhaps from PIE *(s)keuk- "to be white" (compare Sanskrit socati "to lighten, glow," sukra- "light, clear, white"). Spanish, Portuguese cisne, Italian cecero are from Medieval Latin cecinus, cicinus, a corruption of the classical Latin word.

late 14c., chilindre, "portable sundial in the shape of a cylinder with a conical top," from Old French cylindre (14c.) and directly from Latin cylindrus "roller, cylinder," from Greek kylindros "a cylinder, roller, roll," from kylindein "to roll," which is of unknown origin.

From 1560s as "a solid figure which may be conceived as generated by the revolution of a rectangle about one of its sides." From 1690s as "chamber of a steam engine in which the force of the steam is exerted on the piston." By 1849 as "part of a revolver which contains the chamber for the cartridges." By 1878 as "cylindrical record for a phonograph."

"having the form or properties of a cylinder," 1640s, probably from cylindric (but this is attested only from 1680s), from Latinized form of Greek kylindrikos, from kylindros (see cylinder) + -al (1).

"one of a pair of plates of brass or bronze which, when struck together, produce a sharp, ringing sound," mid-15c., from Old English cimbal and from Old French cymbale (13c.), both from Latin cymbalum, from Greek kymbalon "a cymbal," from kymbē "bowl, drinking cup." This previously has been connected with Sanskrit kumbha-, Avestan xumba- "pot;" Middle Irish comm, cummal. Beekes writes that, for structural reasons, "the word cannot be inherited. It is rather a 'Wanderwort', which fits a vessel term very well."

"of or pertaining to the Welsh" and their kindred, the Cornish and Bretons, by 1833, from Welsh Cymru "Wales," Cymry "the Welsh," plural of Cymro, probably from ancient combrox "compatriot," from British Celtic *kom-brogos, from collective prefix *kom- (see com-) + *brogos "district," from PIE root *merg- "boundary, border." Compare Allobroges, name of a warlike people in Gallia Narbonensis, literally "those from another land." As from 1833 as a noun, "the language of the Cymry."

"form of madness in which the afflicted imagines himself to be a dog," 1590s, from Latinized form of Greek kynanthropos "of a dog-man,"  from kyōn (genitive kynos) "dog" (from PIE root *kwon- "dog") + anthrōpos "male human being, man" (see anthropo-).

1550s, "one of the ancient sect of philosophy founded by Antisthenes," from Latinized form of Greek kynikos "a follower of Antisthenes," literally "dog-like," from kyōn (genitive kynos) "dog" (from PIE root *kwon- "dog").

Supposedly the name is a reference to the coarseness of life and sneering surliness of the philosophers, and the popular association even in ancient times was "dog-like" (Lucian has kyniskos "a little cynic," literally "puppy").

But more likely it is from Kynosarge "The Gray Dog," the name of the gymnasium outside ancient Athens (for the use of those who were not pure Athenians) where Antisthenes (a pupil of Socrates), taught. Diogenes was the most famous. Meaning "sneering sarcastic person" is from 1590s. As an adjective from 1630s.

[Diogenes] studied philosophy under Antisthenes, a crusty type who hated students, emphasized self-knowledge, discipline, and restraint, and held forth at a gymnasium named The Silver Hound in the old garden district outside the city. It was open to foreigners and the lower classes, and thus to Diogenes. Wits of the time made a joke of its name, calling its members stray dogs, hence cynic (doglike), a label that Diogenes made into literal fact, living with a pack of stray dogs, homeless except for a tub in which he slept. He was the Athenian Thoreau. [Guy Davenport, "Seven Greeks"]