Underextend

Part of speech: verb

Definitions

1. To use a word in a narrower range of situations than adult speakers would, as when a child applies the term dog only to their own pet
2. Applying a term to fewer instances than its conventional meaning covers, especially in describing how young learners restrict a word's use
3. Restricting the reference of a word more tightly than the standard usage of the language allows, a common pattern in early language acquisition

Etymology: "Underextend" is a plain compound: the prefix "under-" joined to "extend," the verb that comes from Latin "extendere," meaning "to stretch out." Here "under-" works in its familiar sense of "less than" or "not enough," so to underextend a word is to stretch its meaning less far than ordinary speakers do. The term is a technical coinage from the study of child language. Children learning to talk often apply a word like "dog" only to the family pet, not to every four-legged animal, so their use of the word falls short of the adult range. Linguists needed a single verb for that pattern, and the prefixed form supplied it by taking an existing verb and reversing its direction. Its counterpart, "overextend," names the opposite habit, in which a child calls every animal "dog."