英语词源字典 - 在线词源网站

decay [decay 词源字典]: 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 etymology, decay origin, 英语词源]
decide: decide: [14] Etymologically, decide denotes a resolving of alternatives or difficulties by cutting through them as if with a knife or a sword – dealing with them ‘at a stroke’. The word comes, perhaps via French décider, from Latin dēcidere, a compound verb formed from the prefix dē- ‘off’ and caedere ‘cut, strike’. It is not clear where this comes from, although Sanskrit khid- ‘press, tear’ has been compared.

Its other descendants in English include chisel, cement, concise, and scissors. (Other verbs for ‘decide’ which contain the basic meaning element ‘cut through’ or ‘separate’ include Latin dēcernere and German entscheiden.)
=> cement, chisel, concise, excise, incision, precise, scissors
decide (v.): late 14c., "to settle a dispute," from Old French decider, from Latin decidere "to decide, determine," literally "to cut off," from de- "off" (see de-) + caedere "to cut" (see -cide). For Latin vowel change, see acquisition. Sense is of resolving difficulties "at a stroke." Meaning "to make up one's mind" is attested from 1830. Related: Decided; deciding.
deciduous (adj.): 1680s, from Latin deciduus "that which falls off," from decidere "to fall off," from de- "down" (see de-) + cadere "to fall" (see case (n.1)). Originally with reference to leaves, petals, teeth, etc.; specific sense of "trees whose leaves fall off" (opposed to evergreen) is from 1778.
decision (n.): mid-15c., from Middle French décision (14c.), from Latin decisionem (nominative decisio) "a decision, settlement, agreement," noun of action from past participle stem of decidere (see decide). Decision making (adjective, also decision-making) is recorded from 1953.
decisive (adj.): 1610s, from Medieval Latin decisivus, from Latin decis-, past participle stem of decidere (see decide). Related: Decisively; decisiveness.