英语词源字典 - 在线词源网站

childish (adj.)[childish 词源字典]: Old English cildisc "proper to a child;" see child + -ish. Meaning "puerile, immature, like a child" in a bad sense is from early 15c. Related: Childishly; childishness.[childish etymology, childish origin, 英语词源]
nicety (n.): mid-14c., "folly, stupidity," from Old French niceté "foolishness, childishness, simplicity," from nice "silly" (see nice). Underwent sense evolution parallel to nice, arriving at "minute, subtle point" 1580s and "exactitude" in 1650s. Phrase to a nicety "exactly" is attested from 1795.
puerility (n.): late 15c., from Middle French puérilité (15c.), from Latin puerilitatem (nominative puerilitas) "childishness," from puerilis "boyish, youthful; childish, trivial, silly," from puer "child, boy," from PIE *pau- (1) "few, little," with sense extended to "small, young" (cognates: Latin putus "boy," Sanskrit putrah "son, boy," Avestan puthra- "son, child;" see few (adj.)).