thumbtack /ˈθʌm.tæk/noun 1verb 1forms 3 noun1 •(US, Canada) A small nail-like tack with a slightly rounded head that can be pressed into place with light pressure from the thumb; used for hanging light articles on a wall or noticeboard.You say that I'm broke my nigga, how is that? Bitch I'm stickin to this paper like a thumbtack — 2016 verb1 •To fix or attach something with a thumbtack.On the particle-board partition that separated his cubicle from the next, Paul had thumbtacked things that might inspire him […] — 1988 formsthumbtacked · thumbtacking · thumbtacks