under- + ruff
underruff (third-person singular simple present underruffs, present participle underruffing, simple past and past participle underruffed)
- (bridge) To ruff with a trump lower than the trump already played by one's opponent
1973, Fred L. Karpin, The Art of Card Reading at Bridge, →ISBN, page 149:
And so, at trick five, when South ruffed a diamond with the board's queen of clubs, East, having a discard to make, found a gorgeous one— he underruffed with seven of trumps!
underruff (plural underruffs)
- An act of underruffing