necessaryyoudaoicibaDictYouDict[necessary 词源字典]
necessary: [14] The original Latin adjective meaning ‘necessary’ was necesse (it was formed with the negative particle ne- from the stem of cēdere ‘yield’, source of English cede, and hence meant etymologically ‘unyielding’). This was subsequently extended to necessārius, and English acquired it via Anglo-Norman *necessarie.
=> cede, concede, proceed[necessary etymology, necessary origin, 英语词源]
necessary (adj.)youdaoicibaDictYouDict
late 14c. "needed, required, essential, indispensable," from Old French necessaire "necessary, urgent, compelling" (13c.), and directly from Latin necessarius "unavoidable, indispensable, necessary," from necesse "unavoidable, indispensable," originally "no backing away," from ne- "not" + cedere "to withdraw, go away, yield" (see cede). The root sense is of that from which there is no evasion, that which is inevitable. Necessary house "privy" is from c. 1600. Necessary evil is from 1540s (the original reference was to "woman").
necessary (n.)youdaoicibaDictYouDict
mid-14c., "needed, required, or useful things; the necessities of life; actions determined by right or law," perhaps from Old French necessaire (n.) "private parts, genitalia; lavatory," and directly from Latin necessarius (n.), in classical Latin "a relation, relative, kinsman; friend, client, patron;" see necessary (adj.).