From Longman Dictionary of Contemporary Englishthumbnailthumb‧nail1 /ˈθʌmneɪl/ adjective → thumbnail sketch/portraitthumbnailthumbnail2 noun [countable] 1 HBHthe nail on your thumb2 a small picture of a document on a computer screen, showing you what it will look like when you print it Click on the thumbnails to view a larger version of each image.
Examples from the Corpus
thumbnail• Nestling between the two spools was a tiny plastic packet, smaller than a thumbnail.• The Blackfeet let each thumbnail grow long, until it crooked like a claw.• Almost immediately her thumbnail found another groove opposite; she pulled, and the star came out about a centimetre.• He'd given up woodwork, having driven a splinter through his thumbnail.• He opened a book with his thumbnail, as if afraid of dirtying his fingers.• He displayed a swollen, bruised digit and a mangled thumbnail.• It takes more than 400 pages of the manual to show thumbnails of them all. 