In music, the word texture is often used in a rather vague way in reference to the overall sound of a piece of music. A piece may be described as having a "thick" texture, or a "light" texture, or other terms taken from outside of music (Aaron Copland's more popular pieces are described as having an "open" texture). The perceived texture of a piece can be affected by the number of parts playing at once, the timbre of the instruments playing these parts and the harmony and rhythms used, among other things.
There are more precise terms which describe the number and relationships between voices:
Monophony (base musical texture) is music with just one part (such as Gregorian chant). According to Adris Butterfield (1997), monophony, "is the dominant mode of the European vernacular genres as well as of Latin song...in polyphonic works, it remains a central compositional principle."
Heterophony is a kind of complex monophony - there is only one melody, but multiple voices each of which play the melody differently.
Polyphony is music with several parts, each independent but related and each as important as the others - none of them are merely accompaniment.
Homophony is music in which the top part has a dominant melody and other parts are subservient to it, moving in the same rhythm.
Monody is 17th century Italian song with a dominant melody and a separate accompaniment.
Note that none of these terms accurately describes the majority of western music made today, featuring a melody and rhythmically free accompaniment; in homophony the accompaniment is not rhythmically free, and monody is typically used in a historically specific way.
A simultaneity is more than one complete musical texture occurring at the same time, rather than in succession.
Ardis Butterfield (1997). "Monophonic song: questions of category", Companion to Medieval & Renaissance Music. Oxford University Press. ISBN 0198165404.
Monophony is a texture comprising a single line of musical tones: that is, a single melody, or intonation, or cantillation.
Other instances of monophony were the songs of the troubadours and trouveres of France in the 11th to 13th centuries, and the Minnesingers of Germany in the 12th to 14th centuries.
Monophony may also have a complex rhythmic element, as when percussion accompanies a melody in some types of Chinese or Indian music.
According to Adris Butterfield (1997), monophony "is the dominant mode of the European vernacular genres as well as of Latin song [1] in polyphonic works, it remains a central compositional principle." Polyphony has two or more independent melodic voices.
Monophony was the first type of texture in the Lutheran Church Hymn or chorale, which became polyphonic around 1524.