sonata

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A composition for one or more solo instruments, one of which is usually a keyboard instrument, usually consisting of three or four independent movements varying in key, mood, and tempo.

Century Dictionary and Cyclopedia

1. n. In music, in the seventeenth and eighteenth centuries, any composition for instruments: opposed to cantata. These old sonatas were usually in more than one movement. The character of their themes and their structure varied widely, those called church sonatas tending to grave themes and a contrapuntal treatment, and the chamber sonatas resembling the canzona and the suite.
2. n. In recent music, an instrumental work, especially for the pianoforte, made up of three or four movements in contrasted rhythms but related keys, one or more of which are written in sonata form. The movements usually include an allegro with or without an introduction, a slow movement (usually adagio, largo, or andante), a minuet or scherzo with or without a trio appended, and a final allegro or presto, which is often a rondo. A certain unity of sentiment or style is properly traceable between the successive movements. The sonata is the most important form of homophonic composition for a single instrument. A sonata for a string quartet is called a quartet, and one for a full orchestra is called a symphony.
3. n. exposition, containing the first subject, followed by the second, properly in the key of the dominant or in the relative major (if the first be minor);
4. n. development or working out, consisting of a somewhat free treatment of the two subjects or parts of them, either singly or in conjunction;
5. n. restatement containing the two subjects in succession, both in the original key, with a conclusion. The succession of sections and the relations of keys are open to considerable variation, and episodes often occur. The sonata form is distinctive of at least one movement of a sonata or symphony, and usually of the first and last; it also appears in many overtures.

Wiktionary

1. n. music A musical composition for one or a few instruments, one of which is frequently a piano, in three or four movements that vary in key and tempo

GNU Webster's 1913

1. n. (Mus.) An extended composition for one or two instruments, consisting usually of three or four movements

WordNet 3.0

1. n. a musical composition of 3 or 4 movements of contrasting forms