What Is A Bass?

Well my friend, one would require more information to provide a decent answer:  Are you referring to the fish, or do you speak of the musical instrument, my dear?  ♥Nassy

Not sure which you were looking for, but hope this helps...
en.wikipedia.org

The deep sound you hear in music. The lowest octave of human song. Pavorracci ( may have spelt wrong) was one of the most talented operatic bass singers of all time.

There's more than one definition for this word but you kept it in the music and entertainment category. So the answer 'll be: The lowest part of the musical range.

Bass is a name given to a number of perciform fish.  Perciformes are bony fish that resemble perch and will often have spines along their fins.  Many bass are pursued for sport and can also be eaten.  Bass will live in both fresh and salt water and their preference can deviate from warm to temperate waters.  Like many popular sport fish, bass are highly sought after because they will put up quite a fight on the other end of the line.

The striped bass is on of the most popular sport fish that belongs to the moronidae group.  They are found in rivers and estuaries.  Temperate bass species can reach a length of 180 cms (70 inches) and are commercially fished in several regions of the world.  These bass have spines directly behind their gills, two dorsal fins, and a forked caudal or rear fin.  Temperate bass are usually migratory and are capable of traveling great distances.  They will all spawn in fresh water during the springtime.  They feed on smaller fish species as well as on crustaceans such as shrimp.  Some temperate bass have been successfully commercially farmed which has allowed fishermen to introduce these fish into depleted waterways.

Centrarchidae are a warm water species of bass that are also known as sunfish, bream, or perch.  They are native only to North America where they are often found in streams and rivers in the eastern United States.  Centrarchidae bass are known for their multiple rayed fins and spines that can come as a painful surprise to an unsuspecting fisherman.  The most famous warm water bass is the largemouth bass that gets its name from its enormous jaw that extends well behind its eyes and allows it to eat large prey.  The largemouth is a muddy green in colour and will lurk in vegetation or artificial pilings to wait for their prey.

Bass do not seem to be at risk at present thanks to careful management and maintenance of stocks.  There are some species that includes the Chilean sea bass that have been given the common name bass even though they do not belong in the perciform family.  Usually these species have a similar dense, low oil flesh as the bass and borrow its name for marketing purposes.