Underdone means not cooked as long as it should have been. Underdone chicken, slightly underdone, sent it back underdone.
For beef it can be a preference and for chicken and pork it is a hazard, which is the whole distinction. A thermometer settles it better than colour, since meat can be pink and safe or brown and not. Underdone is also used of an argument that needed more work.
1adjectiveunderdoneNot cooked as long as it should have been.
“The potatoes were underdone and still hard in the middle.”
underdone is a quality of cooking.
From under- + done.
Etymology from Wiktionary, CC BY-SA