Quenching is a general term for non-radiative de-excitation. One major reason for non-radiative de-excitation is collisions. As a consequence is the quenching often heavily dependent on pressure and temperature. Quenching poses a problem for non-instant spectroscopic methods, such as laser-induced fluorescence.
In metallurgy, quenching is the rapid cooling of a metal (most commonly steel) to lock it into a hard crystal structure rather than allow it to cool slowly and revert to a softer structure.
