What does "sonata" mean?

Sonata: An extended composition for one or two instruments, consisting usually of three or four movements; as, Beethoven's sonatas for the piano, for the violin and piano, etc. Note: The same general structure prevails in symphonies, instrumental trios, quartets, etc., and even in classical concertos. The sonata form, distinctively, characterizes the quick opening movement, which may have a short, slow introduction; the second, or slow, movement is either in the song or variation form; third comes the playful minuet of the more modern scherzo; then the quick finale in the rondo form. But both form and order are sometimes exceptional.