/thum"nayl'/ , n.
1. the nail of the thumb.
2. anything quite small or brief, as a small drawing or short essay.
3. Print. a small, rough dummy.
4. Also called porkchop . Journ., Print. a half-column portrait in a newspaper.
adj.
5. quite small or brief; concise: a thumbnail description of Corsica.
v.t.
6. to make a thumbnail sketch or description of.
[ 1595-1605; THUMB + NAIL ]