mid-15c., "pertaining to infants," from Late Latin infantilis "pertaining to an infant," from infans "young child" (see infant). Sense of "infant-like" is from 1772.
Entries linking to infantile
The Romans extended the sense of Latin infans to include older children, hence French enfant "child," Italian fanciullo, fanciulla. In English the word formerly also had the wider sense of "child" (commonly reckoned as up to age 7). The common Germanic words for "child" (represented in English by bairn and child) also are sense extensions of words that originally must have meant "newborn."
*bhā-; Proto-Indo-European root meaning "to speak, tell, say."
It forms all or part of: abandon; affable; anthem; antiphon; aphasia; aphonia; aphonic; apophasis; apophatic; ban (n.1) "proclamation or edict;" ban (v.); banal; bandit; banish; banlieue; banns (n.); bifarious; blame; blaspheme; blasphemy; boon (n.); cacophony; confess; contraband; defame; dysphemism; euphemism; euphony; fable; fabulous; fado; fairy; fame; famous; fandango; fatal; fate; fateful; fatuous; fay; gramophone; heterophemy; homophone; ineffable; infamous; infamy; infant; infantile; infantry; mauvais; megaphone; microphone; monophonic; nefandous; nefarious; phatic; -phone; phone (n.2) "elementary sound of a spoken language;" phoneme; phonetic; phonic; phonics; phono-; pheme; -phemia; Polyphemus; polyphony; preface; profess; profession; professional; professor; prophecy; prophet; prophetic; quadraphonic; symphony; telephone; xylophone.
It is the hypothetical source of/evidence for its existence is provided by: Greek pheme "speech, voice, utterance, a speaking, talk," phōnē "voice, sound," phanai "to speak;" Sanskrit bhanati "speaks;" Latin fari "to say," fabula "narrative, account, tale, story," fama "talk, rumor, report; reputation, public opinion; renown, reputation;" Armenian ban, bay "word, term;" Old Church Slavonic bajati "to talk, tell;" Old English boian "to boast," ben "prayer, request;" Old Irish bann "law."
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