What is gmVπ of a Transistor?

GmVπ of a Transistor is the current gain of the transistor.

Ib is the unamplified current that travels into the base of the transistor. This base current, Ib, then gets amplified by a certain factor, β, and produces the amplified current βib. GmVπ is equal to βib. It is another way to calculate the current gain of a transistor.