Etymology
Advertisement
decay (v.)

late 15c., "to decrease," also "to decline, deteriorate, lose strength or excellence," 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 "off" (see de-) + Latin cadere "to fall" (from PIE root *kad- "to fall").

Transitive sense of "cause to deteriorate, cause to become unsound or impaired" is from 1530s. Sense of "decompose, rot" is from 1570s. Related: Decayed; decaying.

Related entries & more 
Advertisement
decease (n.)
Origin and meaning of decease

"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 "to go" (from PIE root *ked- "to go, yield"). Still used with a tinge of euphemism.

Related entries & more 
decease (v.)
Origin and meaning of decease

"to die, depart from life," early 15c., decesen, from decease (n.). Related: Deceased; deceasing.

Related entries & more 
deceased (adj.)

mid-15c., "dead, departed from life," past-participle adjective from decease (v.). As a verbal noun meaning "dead person, those who are dead," from early 17c.

Related entries & more 
decedent (n.)

1730, "dead person," now mostly as a term in U.S. law, from Latin decedentem, present participle of decedere "to die, to depart" (see decease (n.)).

Related entries & more 
Advertisement
deceit (n.)

c. 1300, "trickery, treachery, lying," from Old French deceite, fem. past participle of deceveir, decevoir, from Latin decipere "to ensnare, take in, beguile, cheat," from de "from" or pejorative (see de-) + capere "to take," from PIE root *kap- "to grasp."

From mid-14c. as "act or practice of deceiving," also "false appearance, illusion." From late 14c. as "quality of being false or misleading."

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. [Century Dictionary]
Related entries & more 
deceitful (adj.)

"full of deceit, tending to mislead," mid-15c., from deceit + -ful. Earlier in the same sense was deceivant (late 14c.). Related: Deceitfully; deceitfulness.

Related entries & more 
deceive (v.)

"mislead by false appearance or statement," 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 (see de-) + combining form of capere "to take," from PIE root *kap- "to grasp." Related: Deceived; deceiver; deceiving.

Related entries & more 
decelerate (v.)

1899, probably a back-formation from deceleration. Related: Decelerated; decelerating.

Related entries & more 
deceleration (n.)

1894, originally in railroading, coined from de- "do the opposite of" + (ac)celeration.

Verily "deceleration" is a word which could only be coined by the Great Western. [Engineering magazine, Feb. 2, 1894]
Related entries & more 

Page 33