Preschool

wiktionary

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pre- +‎  school

etymonline

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preschool (adj.)

also pre-school, "of or pertaining to the time before a child is old enough for school," 1886, from pre- "before" + school (n.); the noun is from 1910, "a nursery school for children of preschool age." Related: pre-schooling; pre-schooler.