reduce
v.
late 14c., "bring back," from Old French reducer (14c.), from Latin reducere "lead back, bring back," figuratively "restore, replace," from re- "back" (see re-) + ducere "bring, lead" (see duke, n.). Meaning "bring to an inferior condition" is 1570s; that of "bring to a lower rank" is 1640s (military reduce to ranks is from 1802); that of "subdue by force of arms" is 1610s. Sense of "to lower, diminish, lessen" is from 1787. Related: Reduced; reducing.
〔李〕[re-=back 后；duc=to lead 引；-e ⇒“to lead back 引导向后退”→] v. ①bring to a lower condition 使降级
〔蒋〕[re-回，向后，duc引；“引回”，“向后引、”→退缩，减退] 减少，缩减
〔李〕[re-=backward向后；duc=to lead引导；-e→“to lead backward引回头，使后退”→] v. ① bring from a higher position to a lower position使降级