Trio

Generally speaking, a trio is a group of three. The word is most often used in music to refer to a group of three musicians. For example, a group of three singers would be called a trio.

The word is also used in chamber music to mean a grouping of three instrumentalists or any piece written for such a grouping. The most common forms of trio in classical music are the piano trio (piano, violin and cello) and the string trio (violin, viola and cello).

Another use of the word in music is to refer to the middle, contrasting section of a piece in ternary form. This usage gives rise to the "minuet and trio" (or the "scherzo and trio") which often appears as the third movement in a symphony, sonata or similar work.

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Trio sex or threesome sex is sexual behavior with three people. This act is commonly called a ménage à trois. Sometimes the sexual attraction is mainly between one of the three and the other two and less between these other two; this may for example apply in the case of three heterosexuals.

There is no country allowing both same-sex marriage and polygamy. Therefore, if three people have a marital bond, this consists of two heterosexual marriages: of one person with two persons of the opposite sex.

See also: group sex

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The movie Threesome (1994) is about a love triangle with two men and a woman, originally heterosexual, but with homosexual feelings also awakening.

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Trio was a German pop group that had a hit in the 1980s with the song "Da da da[?]".