noun. the inaccurate limitation of the utilization of a term or word, which is a mistake typically made by young kids leaning language.

UNDEREXTENSION: "You'll need to address underextension at least once in your papers."
Cite this page: N., Pam M.S., "UNDEREXTENSION," in PsychologyDictionary.org, April 29, 2013, https://psychologydictionary.org/underextension/ (accessed May 16, 2021).