Roche

Roche is a convention for use after the opponents have opened 1NT. It's fairly simple: A 2 overcall shows 12-14 HCP, balanced or semi-balanced, with 3+ clubs. All other overcalls are natural.

The idea behind Roche is to try finding game opposite an ACOL weak 1NT when your side holds two (semi-)balanced, 12+ point hands. Playing traditional methods, the auction might otherwise go 1NT-Pass-Pass-Pass.

Responses to the 2 overcall

Pass shows 4+ clubs, no 5-card suit, and no interest in game. For example, a weak 4333.
2// show 5+ cards in the bid suit, and are non-forcing.
2NT is invitational.

Origins

Roche originated in the UK but I don't know who (or where) it was named for. I also cannot find more information about the 3-level responses. Presumably they show good hands with invitational or game-forcing values. If you have any idea, please let me know.

Roche has since become obsolete in tournament play, in favor of more advanced 1NT defenses like DONT and Brozel.