Definitionen
1.NounThe fingernail on the thumb.
2.NounA rough sketch (e.g., the size of one's thumbnail).
3.NounA small picture, used as a compact representation of a larger image.
4.NounA picture displayed by posts and videos pre-clicked conveying the matters discussed/shown in that post.
5.VerbTo describe concisely.
6.VerbTo create a smaller representation of (a larger image).