a tack with a wide, flat head that can be pressed into a board, etc. with the thumb
A tack with a smooth, rounded head that can be pressed into place with the thumb.
transitive verbthumb·tacked, thumb·tack·ing, thumb·tacks
To affix with a thumbtack.
(third-person singular simple present thumbtacks, present participle thumbtacking, simple past and past participle thumbtacked)
- To fix or attach something with a thumbtack.