An image of a graphic or document that is reduced in size so that it serves as an icon of a larger image or to allow multiple images to be viewed on a screen simultaneously or to be transmitted more rapidly.
A rough sketch (e.g., the size of one's thumbnail).
Of, relating to, or of the size of a thumbnail.
American Heritage Medicine
Very small, brief, or concise.
A thumbnail sketch.
Webster's New World
To generate a reduced size image of (a graphic or document).