roof

(noun) a protective covering that covers or forms the top of a building.

(noun) protective covering on top of a motor vehicle.

(noun) the inner top surface of a covered area or hollow space. Examples: "The roof of the cave was very high." "I could see the roof of the bear's mouth."

(noun) an upper limit on what is allowed. Synonyms: ceiling, cap. Examples: "He put a ceiling on the number of women who worked for him." "There was a roof on salaries." "They established a cap for prices."

(verb) provide a building with a roof; cover a building with a roof.