solo (n.)

1690s, "piece of music for one voice or instrument," from Italian solo, literally "alone," from Latin solus "alone" (see sole (adj.)). As an adjective in English from 1712, originally in the non-musical sense of "alone, unassisted;" in reference to aircraft flying from 1909. The verb is first attested 1858 in the musical sense, 1886 in a non-musical sense. Related: Soloed; soloing.

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Definitions of solo from WordNet
solo (n.)
any activity that is performed alone without assistance;
solo (n.)
a musical composition for one voice or instrument (with or without accompaniment);
solo (n.)
a flight in which the aircraft pilot is unaccompanied;
solo (v.)
fly alone, without a co-pilot or passengers;
solo (v.)
perform a piece written for a single instrument;
solo (adv.)
without anybody else or anything else;
he flew solo
Synonyms: alone / unaccompanied
solo (adj.)
composed or performed by a single voice or instrument;
a passage for solo clarinet