Real Dictionary

muff
countable noun: A muff is a piece of fur or thick cloth shaped like a short hollow cylinder. You wear a muff on your hands to keep them warm in cold weather.
plural noun: Muffs are the same as earmuffs.
verb: If you muff something, you do it badly or you make a mistake while you are doing it, so that it is not successful.

muff in American English
a cylindrical covering of fur or other soft material into which the hands are placed from either end for keeping them warm
to do (something) badly or awkwardly
noun: a thick, tubular case for the hands, covered with fur or other material, used by women and girls for warmth and as a handbag

muff in British English 1
noun: an open-ended cylinder of fur or cloth into which the hands are placed for warmth

muff in British English 2
noun: any unskilful play in a game, esp a dropped catch
verb: to perform (an action) awkwardly