Real Dictionary

capo in American English 1
a device fastened over the fingerboard as of a guitar to shorten the strings uniformly and facilitate playing in a different key
noun: any of various devices for a guitar, lute, banjo, etc., that when clamped or screwed down across the strings at a given fret will raise each string a corresponding number of half tones

capo in American English 2
a chieftain in a criminal organization such as the Mafia
noun: the chief of a branch of the Mafia

capo in British English 1
noun: a device fitted across all the strings of a guitar, banjo, etc, so as to raise the pitch of each string simultaneously

capo in British English 2
noun: the presumed title of a Mafia leader