from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Informal A small boy.
- n. Informal A small amount or degree; a bit.
- idiom a tad To a small degree; somewhat: acting a tad silly; a tad uncomfortable.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A small amount; a little bit.
Perhaps short for tadpole.(American Heritage® Dictionary of the English Language, Fourth Edition)
1877, ‘young or small child’, probably a shortened form of tadpole. The extended meaning ‘small amount’ is first recorded 1915. (Wiktionary)