英语词源字典 - 在线词源网站

decathlon (n.)[decathlon 词源字典]: 1912, from deca "ten" (see ten) + Greek athlon "contest, prize," which is of uncertain origin. A modern Olympic event consisting of 10 challenges.[decathlon etymology, decathlon origin, 英语词源]
decay (v.): late 15c., "to decrease," from Anglo-French decair, Old North French decair (Old French decheoir, 12c., Modern French déchoir) "to fall, set (of the sun), weaken, decline, decay," from Vulgar Latin *decadere "to fall off," from de- (see de-) + Latin cadere "to fall" (see case (n.1)). Meaning "decline, deteriorate" is c. 1500; that of "to decompose, rot" is from 1570s. Related: Decayed; decaying.
decay (n.): mid-15c., "deterioration, decline in value," from decay (v.). Meaning "gradual decrease in radioactivity" is from 1897.
decease (n.): "death," early 14c., from Old French deces (12c., Modern French décès) "decease, death," from Latin decessus "death" (euphemism for mors), also "a retirement, a departure," from decess-, past participle stem of decedere "die, depart, withdraw," literally "to go down," from de- "away" (see de-) + cedere "go" (see cede). Still used with a tinge of euphemism.
decease (v.): "to die," early 15c., from decease (n.). Related: Deceased; deceasing
deceased (adj.): late 15c., past participle adjective from decease (v.). As a verbal noun meaning "dead person, those who are dead," from early 17c.
decedent (n.): 1730, "dead person," mostly as a term in law, from Latin decedentem, present participle of decedere "to die, to depart" (see decease (n.)).
deceit (n.): c. 1300, from Old French deceite, fem. past participle of deceveir (see deceive).
Deceit is a shorter and more energetic word for deceitfulness, indicating the quality; it is also, but more rarely, used to express the act or manner of deceiving. The reverse is true of deception, which is properly the act or course by which one deceives, and not properly the quality; it may express the state of being deceived. Fraud is an act or series of acts of deceit by which one attempts to benefit himself at the expense of others. It is generally a breaking of the law; the others are not. [entry for "deceit" in "The Century Dictionary and Cyclopedia," 1902]
deceitful (adj.): mid-15c., from deceit + -ful. Related: Deceitfully; deceitfulness.
deceive (v.): c. 1300, from Old French decevoir "to deceive" (12c., Modern French décevoir), from Latin decipere "to ensnare, take in, beguile, cheat," from de- "from" or pejorative + capere "to take" (see capable). Related: Deceived; deceiver; deceiving.
decelerate (v.): 1899, back-formation from deceleration. Related: Decelerated; decelerating.
deceleration (n.): 1894, originally in railroading, coined from de- "do the opposite of" (see de-) + (ac)celeration.
Verily "deceleration" is a word which could only be coined by the Great Western. ["Engineering," Feb. 2, 1894]
December (n.): c. 1000, from Old French decembre, from Latin December, from decem "ten" (see ten); tenth month of the old Roman calendar, which began with March.

The -ber in four Latin month names is probably from -bris, an adjectival suffix. Tucker thinks that the first five months were named for their positions in the agricultural cycle, and "after the gathering in of the crops, the months were merely numbered."
If the word contains an element related to mensis, we must assume a *decemo-membris (from *-mensris). October must then be by analogy from a false division Sep-tem-ber &c. Perhaps, however, from *de-cem(o)-mr-is, i.e. "forming the tenth part or division," from *mer- ..., while October = *octuo-mr-is. [T.G. Tucker, "Etymological Dictionary of Latin"]
decency (n.): 1560s, "appropriateness," from Latin decentia "comeliness, decency," from decentem "becoming, fitting" (see decent). Meaning "modesty" (i.e. "appropriateness to standards of society") is from 1630s.
decennial (adj.): 1680s, from Latin decennium, from decennis "of 10 years," from decem "ten" (see ten) + annus "year" (see annual). For vowel change, see biennial.
decent (adj.): 1530s, "proper to one's station or rank," also "tasteful," from Middle French décent, or directly from Latin decentem (nominative decens) "becoming, seemly, fitting, proper," present participle of decere "to be fitting or suitable," from PIE *deke-, from root *dek- "to take, accept, to receive, greet, be suitable" (cognates: Greek dokein "to appear, seem, think," dekhesthai "to accept;" Sanskrit daśasyati "shows honor, is gracious," dacati "makes offerings, bestows;" Latin docere "to teach," decus "grace, ornament"). Meaning "kind, pleasant" is from 1902. Are you decent? (1949) was originally backstage theater jargon for "are you dressed."
decentralization (n.): 1839, from de- + centralization.
decentralize (v.): 1840 (implied in decentralized), probably a back-formation from decentralization. Related: Decentralizing.
deception (n.): early 15c., from Middle French déception (13c., decepcion) or directly from Late Latin deceptionem (nominative deceptio) "a deceiving," from Latin decept-, past participle stem of decipere (see deceive).
deceptive (adj.): 1610s, from French deceptif (late 14c.), from Medieval Latin deceptivus, from decept-, past participle stem of Latin decipere (see deceive). Earlier in this sense was deceptious (c. 1600), from French deceptieux, from Medieval Latin deceptiosus, from deceptionem. Related: Deceptively; deceptiveness.