IPA: //ˈpriːˌskuːlər//
KK: /ˈpriːˌskuːlər/
A young child who is too young to go to kindergarten, usually between the ages of three and five, and is enrolled in a preschool program.
My daughter is a preschooler and loves to play with her friends at school.
Preschooler → It is formed from "pre-" (meaning before) and "school" (from Old English *scol*, meaning a place of learning) and "-er" (meaning a person who). A preschooler is a person who is before school age, typically a young child not yet attending school.
Think of someone who is 'before' ('pre-') going to a 'place of learning' ('school') — that's why a preschooler is a young child not yet in school.