1.VerbTo mark items on a list (with a checkmark or by crossing them out) that have been chosen for keeping or removal or that have been dealt with (for example, completed or verified as correct or satisfactory).
"Check off the items on the list that interest you.; Check off the correct answer to each question."
2.VerbTo carry out a decision recorded through the process of checking off an item on a list, including dealing with it, removing it from the possible choices, or removing the not checked items from further consideration.
3.VerbTo deduct union members' dues from their wages.
4.VerbTo request protection by prison authorities.
"He's not in gen-pop anymore because he checked off."