Checkless

Checkless chess is a chess variant where checks are illegal unless it is checkmate. In a chess problem, this is often accompanied by another category, like helpmate. In a checkless helpmate problem, both players still cooperate to achieve checkmate, but without checks. Consequently, a check is also considered checkmate, and therefore legal, if the only responses are non-checkmating checks.

If that last sentence is confusing, here's an example:

In this example position, White just played Qf6#, and that's checkmate because the only moves that Black could play to get out of the check are Kd7 and Kxf6, but they are illegal since they would check White without checkmating them.