multiplyyoudaoicibaDictYouDict[multiply 词源字典]
multiply: [13] Multiply is one of a large family of English words based on Latin multus ‘much’, a word of uncertain origin which may be related to Greek mála ‘very’ and Latin melior ‘better’. Multiply itself comes from the Latin derivative multiplicāre, formed with the element plic- ‘fold’ found also in complicated, explicit, etc, and therefore very closely parallel to the native English compound manifold.

Other members of the family include multiple [17], from late Latin multiplus (the -plus is a relative of the -plic- in multiplicāre); multitude [14], from Latin multitūdō ‘crowd’, formed with the abstract noun suffix -tūdō; and of course the host of words formed since the 16th century with the prefix multi-, including multifarious [17] (based on Latin -fārius ‘doing’), multilateral [17], multinational [20], multiracial [20], and multistorey [20].
=> fold[multiply etymology, multiply origin, 英语词源]
multiply (v.)youdaoicibaDictYouDict
mid-12c., multeplier, "to cause to become many," from Old French multiplier, mouteplier (12c.) "increase, get bigger; flourish; breed; extend, enrich," from Latin multiplicare "to increase," from multiplex (genitive multiplicis) "having many folds, many times as great in number," from comb. form of multus (see multi-) + -plex "-fold," from PIE *plek- "to plait" (see ply (v.1.)). Mathematical sense is attested from late 14c. Related: Multiplied; multiplying.