cap

noun

a tight-fitting headdress
a top (as for a bottle)
something serving as a cover or protection
the upper part of a column that supports the entablature

capital
in dentistry, dental appliance consisting of an artificial crown for a broken or decayed tooth
“I don't have any caps yet.”
crowncrownworkjacketjacket crown
a mechanical or electrical explosive device or a small amount of explosive

detonatordetonating device
an upper limit on what is allowed

ceilingroof
a protective covering that is part of a plant

hood
a fruiting structure resembling an umbrella or a cone that forms the top of a stalked fleshy fungus such as a mushroom

pileus

verb

to restrict the number or amount of
“We had to cap the number of people we can accept into our club”
to lie at the top of
“Snow capped the mountains”
crest