Acapella- singers performing without instrumental accompaniment.
Cantabile- in a singing style
airy voice usually in higher pitches.
Glissando- sliding quickly between 2 notes
Passagio- singing voice where register transitions occur.
Rubato- slight speeding up or slowing down of the tempo of a piece
Tessitura- most comfortable singing range of a singer
Vibrato- rapid repeated slight pitch variation during a sustained note