The noun cap has 8 senses (first 4 from tagged texts)
1. (10) cap -- (a tight-fitting headdress)
2. (2) cap -- (a top (as for a bottle))
3. (1) detonator, detonating device, cap -- (a mechanical or electrical explosive device or a small amount of explosive; can be used to initiate the reaction of a disrupting explosive)
4. (1) cap -- (something serving as a cover or protection)
5. cap, pileus -- (a fruiting structure resembling an umbrella that forms the top of a stalked fleshy fungus such as a mushroom)
6. ceiling, cap -- (an upper limit on what is allowed; "they established a cap for prices")
7. crownwork, cap -- (dental appliance consisting of an artificial crown for a tooth)
8. capital, chapiter, cap -- (the upper part of a column that supports the entablature)
Overview of verb cap
The verb cap has 2 senses (first 1 from tagged texts)
1. (3) cap, crest -- (lie at the top of; "Snow capped the mountains")
2. cap -- (restrict the number or amount of; "We had to cap the number of people we can accept into our club")