Noun

1. A tight-fitting headdress
2. A top (as for a bottle)
3. A mechanical or electrical explosive device or a small amount of explosive; can be used to initiate the reaction of a disrupting explosive
4. Something serving as a cover or protection
5. A fruiting structure resembling an umbrella or a cone that forms the top of a stalked fleshy fungus such as a mushroom
6. A protective covering that is part of a plant
7. An upper limit on what is allowed
8. (dentistry) dental appliance consisting of an artificial crown for a broken or decayed tooth
9. The upper part of a column that supports the entablature

Verb

1. Lie at the top of
2. Restrict the number or amount of