approach-forcing

Coined by Ely Culbertson in the early 1930's to describe the bidding system that he invented.

1(bridge) A bidding system in which the responder does not support a partner's bid suit without 4 card support or 3 cards plus a Queen or higher, never passes an opening 1 bid while holding one and a half honor tricks or more, always responds with an indication of hand strength, and in which a 2 opener or jump bid is considered forcing to game. No Trump is used as a negative response when forced to bid.