A capella: Italian, "In the manner of a chapel." This term originally (i.e., in the nineteenth century) referred to polyphonic sacred choral music performed without instrumental accompaniment. Because this was the kind of music performed by the Sistine Chapel choir at papal liturgies in the 19th century, it was assumed to be the authentic practice of Palestrina and other Renaissance composers. In fact it seems to have been common in the Renaissance to have instruments double some or all of the vocal parts.
Frauenchor: German, "Women's chorus."
Mannerchor: German, "Men's chorus."
Alteration: The raising or lowering of a pitch by means of an accidental. In musical notation, an accidental is any of the symbols (sharp, flat, double sharp, double flat, natural) used to raise or lower a pitch by one or two semitones or to cancel a previous sign or part of a key signature.
Flat: A musical symbol that indicates that a pitch is lowered by one semitone.
Sharp: A musical symbol that indicates that a pitch is raised by one semitone.
Fugue: A composition written systematically in imitative polyphony, usually with a single main theme--the fugal subject-- which is stated successively in all the voices.
Augmentation: The statement of a theme in uniformly longer note-values than those in which it was originally heard. Thus, if the ratio between old and new values is 2 to 1, in augmentation what was originally a quarter note becomes a half note.
Inversion: The inversion of a melody is a melody whose contour is the mirror image of the original melody. Thus, where the original melody rises, the inversion falls and vice versa.
Stretto: In a fugue, the imitative treatment of the subject at a shorter interval of time than is employed in the initial exposition. In other words, the subject enters in a new voice before it has finished in the preceding voice. Because stretto is experienced as a heightening of tension, the technique is often reserved for a climactic moment near the end.
Ritornello: Italian, "Little return." The orchestral material at the beginning of a concerto grosso or other Baroque instrumental work which always returns later in the piece, as a kind of refrain.