decay: [15] The notion underlying decay and its close relative decadence is of a ‘falling off’ from a condition of health or perfection. Decay comes from Old Northern French decair, a descendant of Vulgar Latin *dēcadere, which in turn came from Latin dēcidere, a compound verb formed from the prefix dē- ‘down, off, away’ and cadere ‘fall’ (source of English case and a wide range of related words). Decadence [16] was acquired via the medieval derivative dēcadentia. To the same word-family belongs deciduous [17], from Latin dēciduus, literally denoting the ‘falling off’ of leaves from trees. => accident, case, chance, decadence, deciduous
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.
例文
1. When not removed，place causes tooth decay and gum disease.
歯垢は除去しないと歯の虫食いや歯肉疾患を引き起こす。
2.There are problems of urban decay and gang violence.
都市の衰退とギャング暴力の問題がある。
3.The phosphate was deposited by the decay of marine microorganisms.
海洋微生物を腐敗させて堆積させてリン酸塩を形成する。
4.The landlord had let the building fall into decay .
大家は放っておいて、家はぼろぼろになっていた。
5.The decay of the meat could have been prevented by proper refrigeration.