ski cap
stocking cap
toboggan cap

He wore a black ski cap, even in summer, they said.

The red puff on the top of his ski cap bobbed.

Next was a burly man wearing a black ski cap.

A black ski cap covered the top of his head.

Outside the window stood a man, a ski cap pulled low over his brow.

The gunman was described as a 6-foot-2 black man with a ski cap and dark clothes.

But he may have been wearing a dark ski cap of the Deerhunter style.

And there was a ski cap pulled down to the top rim of his glasses.

Both wore black ski caps, but their faces were uncovered.

Maybe she's that one in the Norwegian ski cap, walking slowly while she reads.