What is "ambrosian chant"

Ambrosian \Am*bro"sian\, a. Of or pertaining to St. Ambrose; as, the Ambrosian office, or ritual, a formula of worship in the church of Milan, instituted by St. Ambrose.

Ambrosian chant, the mode of signing or chanting introduced by St. Ambrose in the 4th century.

Chant \Chant\, n. [F. chant, fr. L. cantus singing, song, fr. canere to sing. See Chant, v. t.]

1. Song; melody.

2. (Mus.) A short and simple melody, divided into two parts by double bars, to which unmetrical psalms, etc., are sung or recited. It is the most ancient form of choral music.

3. A psalm, etc., arranged for chanting.

4. Twang; manner of speaking; a canting tone. [R.]

   His strange face, his strange chant.
   --Macaulay.

   Ambrosian chant, See under Ambrosian.

   Chant royal [F.], in old French poetry, a poem containing five strophes of eleven lines each, and a concluding stanza. -- each of these six parts ending with a common refrain.

   Gregorian chant. See under Gregorian. [1913 Webster] ||

Ambrosian chant (also known as Milanese chant) is the liturgical plainchant repertory of the Ambrosian rite of the Roman Catholic Church, related to but distinct from Gregorian chant. It is primarily associated with the Archdiocese of Milan, and named after St. Ambrose much as Gregorian chant is named after Gregory the Great. It is the only surviving plainchant tradition besides the Gregorian to maintain the official sanction of the Roman Catholic Church.