I. ˈ ̷ ̷ˌ ̷ ̷ noun
Etymology: thumb (I) + mark
1. : an impression left by a thumb especially when used as a mark of identification
2. : a depression in the sides of a single comb of a fowl that is a defect in show birds
II. transitive verb
: to mark with the thumb ; also : to take a thumbmark of (as for identification)