from The American Heritage® Dictionary of the English Language, 4th Edition
- transitive v. To do to an insufficient degree, especially to cook for too short a time.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To put under, subject.
- v. To do something insufficiently; especially to undercook.
- v. To act below one's abilities; do less than one can.
- v. To do less than is requisite.
from the GNU version of the Collaborative International Dictionary of English
- intransitive v. To do less than is requisite or proper; -- opposed to
- transitive v. To do less thoroughly than is requisite; specifically, to cook insufficiently; ; -- opposed to
from The Century Dictionary and Cyclopedia
- To put under; subject.
- To do less thoroughly than is requisite; especially, to cook insufficiently: as, the beef is underdone.
- To act below one's abilities; do less than one can.
- To do less than is requisite.
From Middle English underdon, from Old English underdōn ("to put under"), from Proto-Germanic *under + *dōnan (“to put”), equivalent to under- + do. Cognate with German unterthun ("to put under, subject"). (Wiktionary)