What does "overdrive" mean???

I came across the term overdrive in a text book n i didnt quite get the meaning....the circuit consisted of 2 mosfest n said tht the overdrive voltage of one of the mosfets is 10 times tht of the other....does overdrive voltage mean the voltage reqd to drive the mosfet into saturation????

I THINK it refers to V-gs for a MOSFET device.

You are taking the gate-source voltage beyond the threshold at which it achieves on state.

My understanding is that overdrive voltage is the area between threshold and saturation, and thus would be the linear region.