snap head

buttonhead

buttonhead
The head of a bar, bolt, rivet, or screw which is hemispherical in shape; usually the head is less than a full hemisphere and has a flat bearing surface.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
Mentioned in ?
References in periodicals archive ?
If the detent snap head sticks, you'll have trouble adjusting the pole.