transitive verb-·did′, -·done′, -·do′ing
to do less than is usual, needed, or desired
transitive verbun·der·did, un·der·done, un·der·do·ing, un·der·does,
To do to an insufficient degree, especially to cook for too short a time.
(third-person singular simple present underdoes, present participle underdoing, simple past underdid, past participle underdone)