Full comp stands for full compensation.
This term is typically used in the context of mortgage rates.
When an originator sells a mortgage at full comp, he/she is earning the standard commission on that loan without any buydowns. (Rate buydowns typically reduce a mortgage originator's compensation.)
A full comp 5-year fixed might net a broker a roughly 110 bps commission, and a bank mortgage specialist about 55 bps, give or take.