Definitions of cap:

• noun:   a tight-fitting headdress
• noun:   a top (as for a bottle)
• noun:   something serving as a cover or protection
• noun:   a fruiting structure resembling an umbrella that forms the top of a stalked fleshy fungus such as a mushroom
• noun:   dental appliance consisting of an artificial crown for a tooth
• noun:   an upper limit on what is allowed

  Example: "They established a cap for prices"

• noun:   the upper part of a column that supports the entablature
• noun:   a mechanical or electrical explosive device or a small amount of explosive; can be used to initiate the reaction of a disrupting explosive
• verb:   restrict the number or amount of

  Example: "We had to cap the number of people we can accept into our club"

• verb:   lie at the top of

  Example: "Snow capped the mountains"

• name:  A surname (very rare: popularity rank in the U.S.: #24847)