intensive (adj.)youdaoicibaDictYouDict[intensive 词源字典]
mid-15c., from French intensif (14c.), from Latin intens-, past participle stem of intendere (see intend). As a noun, 1813, from the adjective. Alternative intensitive is a malformation. Intensive care attested from 1958. Related: Intensively.[intensive etymology, intensive origin, 英语词源]