THUMB n.
he had of gold a ring. Chaucer. Thumb band, a twist of anything as thick as the thumb. Mortimer. -- Thumb blue, indigo in the form of small balls or lumps, used by washerwomen to blue linen, and the like. -- Thumb latch, a door latch having a lever formed to be pressed by the thumb. -- Thumb mark. (a) The mark left…