mandolin, musical instrument of the lute family, with a half-pear-shaped body, a fretted neck, and a variable number of strings, plucked with the fingers or with a plectrum. The earlier mandolin, with five double strings, was developed from the mandola, a 17th-century lute. The Neapolitan mandolin, a smaller type having four pairs of strings, became popular in the 18th cent. and is the usual present-day mandolin. In popular music it is generally played with a tremolo motion. Notable uses of the mandolin in serious music are in Mozart's Don Giovanni and in pieces by Beethoven and Mahler.

Small stringed instrument related to the lute. It evolved in the 17th century in Italy, but its present form was strongly influenced by the 19th-century maker Pasquale Vinaccia (1806–82) of Naples. It has a pear-shaped body with a deeply vaulted back, a short fretted fingerboard, and four pairs of steel strings. (The American folk mandolin is a shallow, flat-backed version.) It is played with a plectrum; each pair of strings is strummed rapidly back and forth to produce a characteristic tremolo.

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