From Middle English underdon, from Old English underdōn (“to put under”), from Proto-Germanic *under + *dōną (“to put”). Equivalent to under- + do. Cognate with German unterthun (“to put under, subject”).
- (transitive, obsolete) To put under, subject.
- (transitive) To do something insufficiently; especially to undercook.
- (intransitive) To act below one's abilities; do less than one can.
- (intransitive) To do less than is requisite.