Old English cildisc "proper to a child;" see child + -ish. Meaning "puerile, immature, like a child" in a bad sense is from early 15c. Similar formation in Old Saxon kindisc, Middle Dutch kintsch, Dutch kindsch, German kindisch. Related: Childishly; childishness.
childish tantrums
childbed
childbirth
childe
Childermas
childhood
childish
childless
childlike
child-proof
children
Chile