Wiktionary
fitted cap
n. (context US English) A cap that is not elasticated or adjustable at the back.
Usage examples of "fitted cap".
Charley put clamps around her temples, then covered her hair with a fitted cap that fell away at the base of her neck.
And his face had a similar slightly ominous composure and awareness, under a thick, close-fitted cap of waving hair the colour of copper beeches.
The bottle had curved sides and a machine-fitted cap of cork and tin.