1. In modal logic, describes a deductive system $\text{L}$ corresponding to a class $S$ of Kripke frames in the sense that $\phi$ is an $\text{L}$-theorem if and only if for every Kripke model whose underlying frame is in $S$, $\phi$ is true at every possible world. Named for philosopher Saul Kripke (1940– ).

2. Any modal logic $\text{L}$ such that there exists a class of frames with respect to which $\text{L}$ is Kripke complete in the former sense.