childish

the word 'childish' is a native english formation, built from the old english noun 'cild', meaning a young person or infant, and the adjectival suffix '-isc', which denoted origin or quality. the suffix '-ish' has germanic roots, cognate with german '-isch' and greek '-iskos', and functions to create adjectives meaning 'having the character of' the noun it attaches to. while 'child' itself has a complex proto-germanic ancestry, possibly related to terms for womb or fetus, the compound 'childish' straightforwardly signifies 'having the qualities of a child'. over time, the word has acquired a connotation of immaturity or foolishness, especially when applied to adults, reflecting a cultural judgment on age-appropriate behavior.

Structure: child (young person) + ish (having the qualities of) child (old english, noun base meaning 'a young person, infant, fetus'), ish (old english, adjective-forming suffix meaning 'of the nature of, belonging to').