Learn That Word

Synonyms for Cap (same or very similar meaning)

WordNet sense 1 (a fruiting structure resembling an umbrella that forms the top of a stalked fleshy fungus such as a mushroom):

WordNet sense 2 (an upper limit on what is allowed):

WordNet sense 3 (a mechanical or electrical explosive device or a small amount of explosive; can be used to initiate the reaction of a disrupting explosive):
detonator, detonating device

WordNet sense 4 (dental appliance consisting of an artificial crown for a tooth):

WordNet sense 5 (the upper part of a column that supports the entablature):
capital, chapiter

WordNet sense 6 (lie at the top of):

From the ODE community, based on WordNetadd/edit