1580s, with a capital -c-, "resembling Cynic philosophers," from cynic + -al (1). By 1660s (with a lower-case -c-) the meaning had shaded into the general one of "disposed to disbelieve or doubt the sincerity or value of social usages or personal character or motives and to express it by sarcasm and sneers, disparaging of the motives of others, captious, peevish." Related: Cynically.

Cynical expresses a perverse disposition to put an unfavorable interpretation upon conduct, or to exercise austerity under profession of a belief in the worthlessness of any offered form of enjoyment. Misanthropic expresses a hatred of mankind as a race. Pessimistic is primarily and generally a philosophical epithet, applying to those who hold that the tendency of things is only or on the whole toward evil. [Century Dictionary]

1670s, "philosophy or doctrines of the Cynics" (indifference to pleasure, stoicism pushed to austerity, asceticism), from cynic + -ism. Meaning "cynical character" is from 1847. For nuances of usage, see humor (n.).

"having a head like a dog," 1825, from Latin, from Greek kyōn (genitive kynos) "dog" (from PIE root *kwon- "dog") + kephalikos "pertaining to the head," from kephalē "head" (see cephalo-). Middle English had cino-cephales "fabled race of dog-headed creatures" (c. 1300).

"something that strongly attracts attention," 1590s, from Middle French cynosure (16c.), from Latin Cynosura, literally "dog's tail," an old name of the constellation (now Ursa Minor) containing what is now (but was not in ancient times) the North Star, the focus of navigation, at the tip of its tail; from Greek kynosoura, literally "dog's tail," from kyōn (genitive kynos; from PIE root *kwon- "dog") + oura "tail" (see arse). Apparently in ancient times the whole constellation was used as a rough indicator of the celestial north pole. Related: Cynosural.

fem. proper name, also a poetic name of the Moon, from Latin Cynthia dea "the Cynthian goddess," epithet of Artemis/Diana, who is said to have been born on Mt. Cynthus (Greek Kynthos) on the isle of Delos.

popular name of a type of evergreen tree noted for its dense, dark foliage and durable, fragrant wood, native to southern Europe and sacred to Pluto, late 12c., from Old French cipres (12c., Modern French cyprès), from Late Latin cypressus, from Latin cupressus, from Greek kyparissos, probably from an unknown pre-Greek Mediterranean language.

Perhaps it is related to Hebrew gopher, name of the tree whose wood was used to make the ark (Genesis vi.14). Extended to similar trees of America, Australia, and Japan. An emblem of mourning for the dead, cypress branches were used at funeral.

1620s, "of Cyprus," from Latin Cyprianus, from Cyprius, from Greek Kyprios (see Cyprus). The island was famous in ancient times as the birthplace of Aphrodite and for erotic worship rituals offered to her there; hence Cyprian also meant "pertaining to Aphrodite," and "licentious, lewd," which is the earliest attested sense in English (1590s), and was applied 18c.-19c. to prostitutes.

1590s as an adjective, "of or pertaining to the island of Cyprus;" 1630s as an adjective, "native of inhabitant of Cyprus," from Latinized form of Greek Kypriotes, from Kypros "Cyprus" (see Cyprus).

large eastern Mediterranean island, late 14c., Cipre, Cipres, from Latinized form of Greek Kypros "land of cypress trees" (see cypress).

ancient Greek colony in Libya; the name is of unknown origin. Cyrenaic (1640s) typically refers to the philosophy ("practical hedonism") of Aristippus of Cyrene (c. 435-c. 356 B.C.E.); as a noun, "a Cyrenaic philosopher," from 1580s.

According to Aristippus, pleasure is the only rational aim, and the relative values of different pleasures are to be determined by their relative intensities and durations. He maintained also that cognition is limited to sensation. [Century Dictionary]