1. The nail of the thumb.
2. Computers An image of a graphic or document that is reduced in size so that it serves as an icon of a larger image. This allows multiple images to be viewed on a screen simultaneously or to be transmitted more rapidly.
1. Of, relating to, or of the size of a thumbnail.
2. Greatly reduced or limited in scale or scope: a thumbnail sketch; a thumbnail biography.
tr.v. thumb·nailed, thumb·nail·ing, thumb·nails
To generate a reduced size image of (a graphic or document).
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.