underextensions

Underextension is a term used in linguistics and cognitive science to describe a type of semantic error where a word's meaning is applied too narrowly. This often occurs in language acquisition, particularly in children, but can also be seen in adults. An underextension happens when a speaker uses a word to refer only to a subset of the objects or situations that the word typically covers.

For example, a child might learn the word "car" and initially only use it to refer to their own family's red car. They might not recognize other types of vehicles, such as trucks, buses, or even other people's cars, as belonging to the category "car." Similarly, a person might use the word "ball" only for a specific type of sports ball, failing to include smaller, softer balls in their understanding.

This phenomenon highlights how learners gradually refine their conceptual categories. Initially, the semantic boundaries are tight, and with more exposure and experience, these boundaries are expanded to encompass the full range of a word's conventional meaning. Underextensions are a normal part of the learning process and are typically overcome as a speaker's vocabulary and understanding of the world develop. They are distinct from overextension, where a word is applied too broadly.