You might be looking for the term polyphonic. Its basically the only term to describe the technique.
The general term would be a quintet.
Singing without instrument accompaniment
The diaphragm is muscle located just beneath the lungs. This muscle is responsible for allowing air in and forcing air out of your body. The term "singing diaphragm" has no relevance, though the muscle is used quite extensively while singing.
Parallelism ~ Apex ~
Bravado is the act of bravery. Ex: The superhero showed great bravado by going into the burning building.
Bravado is a pretence of courage, a false show of bravery.
Lance Bravado was born on 1985-09-16.
The Bravado bra is special because it is designed specially for women who have just given birth. The Bravado bra is a nursing bra and provides for the special needs of nursing women.
Most stores or retail sites that sell nursing bras carry the Bravado brand. If you can't find them locally, they can also be purchased directly through Bravado Designs.
I've always understood it to mean singing without vibrato.
elan
It means the same as the word Cantabile which means 'in a singing style'.
In a singing style
Bravado.
Just that. Jazz. No special term.
Musical pieces that don't have any lyrics or singing are called instrumental pieces.