Online Etymology Dictionary

Ceres: Roman goddess of agriculture (identified with Greek Demeter), also the name given to the first-found and largest asteroid (discovered 1801); see cereal. Her festival, Cerealia, was April 10.
Cereus (n.): cactus genus, 1730, from Latin cereus "waxen, waxy," from cera "wax" (see cere (n.)). So called from its shape, which suggests a candle.
ceriph (n.): "lines at the top or bottom of a letter;" see sans-serif.
cerise (n.): shade of red, 1858, from French cerise, from rouge-cerise "cherry-red," from cerise "cherry" (see cherry).
cerium (n.): element, first isolated in pure form in 1875, named for ceria, the name of the earth from which it was taken, which was discovered in 1803 and named by Berzelius and Hissinger for Ceres, the minor planet, which had been discovered in 1801 and named for the Roman goddess Ceres. With metallic element ending -ium.
cero-: word-forming element meaning "waxy," from Latinized form of Greek kero-, comb. form of keros (see cere (n.)).
ceromancy (n.): "divination by means of melted wax dripped in water" (the shapes supposedly previsioning a future spouse, etc.), 1650s, from French ceromancie, Medieval Latin ceromantia; see cere (n.) + -mancy.
cert: colloquial abbreviation of certain or certainty, attested from 1889.
certain (adj.): c. 1300, "determined, fixed," from Old French certain "reliable, sure, assured" (12c.), from Vulgar Latin *certanus, from Latin certus "sure, fixed, settled, determined" (also source of Italian certo, Spanish cierto), originally a variant past participle of cernere "to distinguish, decide," literally "to sift, separate" (see crisis).

Of persons, "full of confidence in one's knowledge or judgment," from mid-14c. Euphemistic use (of a certain age, etc.) attested from mid-18c. Certainer, certainest were common to c. 1750, but have fallen from proper use for some reason. Expression for certain "assuredly" is attested by early 14c.
certainly (adv.): c. 1300, in all main modern senses, from certain + -ly (2).
certainty (n.): c. 1300, certeynte, "surety, pledge," from Anglo-French certeinté (late 13c.), Old French certainete "certainty," from Latin or Vulgar Latin *certanitatem (source of Old Spanish certanedad); see certain. Meaning "that which is certain" is attested from early 14c.; meaning "quality of being certain" is from mid-14c.
certes (adv.): mid-13c., from Old French certes, from Vulgar Latin certas, from Latin certe, adverb from certus (see certain).
certifiable (adj.): 1846, from certify + -able. Meaning "so deranged as to be certifiably insane" is recorded from 1912.
certificate (n.): early 15c., "action of certifying," from French certificat, from Medieval Latin certificatum "thing certified," noun use of neuter past participle of certificare (see certify). Of documents, from mid-15c., especially a document which attests to someone's authorization to practice or do something (1540s).
certificated (adj.): 1610s, past participle adjective from obsolete certificate (v.), from Medieval Latin certificatus, past participle of certificare (see certify).
certification (n.): early 15c., "notification;" mid-15c., "demonstration, proof," from Medieval Latin certificationem (nominative certificatio), noun of action from past participle stem of Late Latin certificare (see certify). Meaning "act of providing with a legal certificate" is from 1881.
certify (v.): mid-14c., "to declare the truth of," also "to vouch for or confirm" (an official record, etc.), from Old French certefiier "make certain, witness the truth of" (12c.), from Late Latin certificare "to certify, to make certain," from Latin certus (see certain) + root of facere "to make, do" (see factitious). Also used in Middle English in broader senses of "inform, give notice; instruct, to direct; to designate." Related: Certified; certifying. Certified public accountant attested from 1896.
certiorari: legal Latin, "to be certified, to be informed or shown," from a word figuring in the opening phrase of such writs from superior to inferior courts seeking the records of a case. Passive present infinitive of certorare "to certify, inform," from certior, comp. of certus "sure" (see certain).
certitude (n.): early 15c., from Middle French certitude "certainty" (16c.), from Late Latin certitudinem (nominative certitudo) "that which is certain," from Latin certus "sure, certain" (see certain).
cerulean (adj.): 1660s, with -an + Latin caeruleus "blue, dark blue, blue-green," perhaps dissimilated from caelulum, diminutive of caelum "heaven, sky," which is of uncertain origin (see celestial). The Latin word was applied by Roman authors to the sky, the Mediterranean, and occasionally to leaves or fields. As a noun, from 1756.
cerumen (n.): "earwax," 1741, medical Latin cerumen, coined by Swiss anatomist Gaspard Bauhin (1560-1624) from Latin cera "wax" (see cere (n.)) on model of albumen; or else from Greek keroumenos "formed of wax."
cerveza (n.): Spanish for "beer," from Latin cervisia "beer" (related to Latin cerea "a Spanish beer"), from a Celtic *kerb- (compare Gaulish curmi, Old Irish cuirm, Middle Irish coirm, Welsh cwrwf, Old Cornish coref "beer"), from Proto-Celtic *kormi-, perhaps from PIE root *krem-, also source of Latin cremare "to burn" (see cremation). "Connection with ceres (as a drink from grain) is very dubious" [Tucker].
cervical (adj.): 1680s, "of the neck," from French cervical, from Latin cervix (see cervix). Meaning "of the neck of the womb" attested by 1860. Related: Cervically.
cervix (n.): early 15c., "ligament in the neck," from Latin cervix "the neck, nape of the neck," from PIE *kerw-o-, from root *ker- (1) "horn, head" (see horn (n.)). Applied to various neck-like structures of the body, especially that of the uterus (by 1702), where it is shortened from medical Latin cervix uteri (17c.). Sometimes in medical writing 18c.-19c. cervix of the uterus to distinguish it from the neck sense.
Cesar: Spanish form of masc. proper name Caesar.
cesarean: alternative spelling of caesarian (see also æ).
cesarian: alternative spelling of caesarian.
cesium (n.): also caesium, rare alkaline metal, 1861, coined by Bunsen and Kirchhoff in 1860 in Modern Latin (caesium), from Latin caesius "blue-gray" (especially of eyes), in reference to the two prominent blue lines in its spectrum, by which it was first identified. With metallic element ending -ium.
cess (n.): "tax, levy," 1530s, short for assess (q.v.).
cessation (n.): mid-15c., cessacyoun "interruption, abdication," from Latin cessationem (nominative cessatio) "a delaying, ceasing, tarrying," noun of action from past participle stem of cessare "delay" (see cease (n.)).
cession (n.): late 14c., "a relinquishing," from Old French cession "cession; death" (13c.), from Latin cessionem (nominative cessio) "a giving up, surrendering," noun of action from past participle stem of cedere "to go away, yield" (see cede). Related: Cessionary.
cesspit (n.): 1864, from cess (see cesspool) + pit (n.).
cesspool (n.): also cess-pool, 1670s, the first element perhaps an alteration of cistern, perhaps a shortened form of recess [Klein]; or the whole may be an alteration of suspiral (c. 1400), "drainpipe," from Old French sospiral "a vent, air hole," from sospirer "breathe," from Latin suspirare "breathe deep" [Barnhart]. Meaning extended to "tank at the end of the pipe," which would account for a possible folk-etymology change in final syllable.

Other possible etymologies: Italian cesso "privy," from Latin secessus "place of retirement" (in Late Latin "privy, drain"); dialectal suspool, from suss, soss "puddle;" or cess "a bog on the banks of a tidal river."
Cestrian: 1703, from Cester, Old English form of Chester, + -ian.
Cetacea (n.): order of marine mammals containing whales, 1830, Modern Latin, from Latin cetus "any large sea creature" (whales, seals, dolphins), from Greek ketos "a whale, a sea monster," which is of unknown origin, + -acea. Hence cetology "the study of whales," first attested 1851 in "Moby Dick."
cetacean (n.): 1836, from Cetacea, name of the order of marine mammals, + -an. As an adjective from 1839.
ceteris paribus: Modern Latin, literally "other things being equal."
cetyl (n.): univalent alcohol radical found in spermaceti, beeswax, etc., 1842, from Latin cetus "whale" (see Cetacea) + -yl.
Ceylon: Portuguese form of Sri Lanka (q.v.). Related: Ceylonese.
cf: see cf.
cf.: abbreviation of Latin confer "compare" (see confer).
cgi: by 2004, initialism (acronym) for computer-generated imagery.
ch: digraph used in Old French for the "tsh" sound. In some French dialects, including that of Paris (but not that of Picardy), Latin ca- became French "tsha." This was introduced to English after the Norman Conquest, in words borrowed from Old French such as chaste, charity, chief (adj.). Under French influence, -ch- also was inserted into Anglo-Saxon words that had the same sound (such as bleach, chest, church) which in Old English still was written with a simple -c-, and into those that had formerly been spelled with a -c- and pronounced "k" such as chin and much.

As French evolved, the "t" sound dropped out of it, so in later loan-words from France ch- has only the sound "sh-" (chauffeur, machine (n.), chivalry, etc.).

It turns up as well in words from classical languages (chaos, echo, etc.). Most uses of -ch- in Roman Latin were in words from Greek, which would be pronounced correctly as "k" + "h," as in blockhead, but most Romans would have said merely "k." Sometimes ch- is written to keep -c- hard before a front vowel, as still in modern Italian.

In some languages (Welsh, Spanish, Czech) ch- can be treated as a separate letter and words in it are alphabetized after -c- (or, in Czech and Slovak, after -h-). The sound also is heard in more distant languages (as in cheetah, chintz), and the digraph also is used to represent the sound in Scottish loch.
cha (n.): "tea," 1590s, also chaw, ultimately from the Mandarin ch'a "tea;" used in English alongside tea when the beverage was introduced.
cha-cha (n.): also cha-cha-cha, type of Latin-American 3-beat ballroom dance, 1954, echoic of the music.
Chablis (n.): light, white Burgundy wine, 1660s, named for town of Chablis southeast of Paris. Made only of Chardonnay grapes. The French word chablis (16c.) is literally "deadwood," fallen from a tree through age or brought down by wind, short for bois chablis, from Old French *chableiz.
chad (n.1): also Mr. Chad, graffiti drawing of a head peering over a fence or wall, with the caption, "Wot, no ______?" (the U.S. version usually had "Kilroy was here"), in reaction to shortages and rationing, 1945, British, of unknown origin.
Chad (n.2): African nation, former French colony (Tchad), independent since 1960, named for Lake Chad, which is from a local word meaning "lake, large expanse of water." An ironic name for such a desert country.
chad (n.3): "hanging flap or piece after a hole is punched in paper," a word unknown to most people until the 2000 U.S. presidential election (when the outcome hinged on partially punched paper ballots in some Florida counties), attested by 1930, of unknown origin.
chador (n.): "cloth worn as a shawl by Muslim women," from Persian chadar "tent, mantle, scarf, veil, sheet, table-cloth."