Definition from Wiktionary, the free dictionary
- (transitive) To render larger, more extended, or more intense, and the like;—used especially of loudspeakers, telescopes, microscopes, etc.
- (transitive, rhetorical) To enlarge by addition or discussion; to treat copiously by adding particulars, illustrations, etc.; to expand; to make much of.
- (transitive) To increase the amplitude of something, especially of an electric current.
Related terms 
to render larger etc.
to increase amplitude