CNF

A propositional formula is a CNF formula, meaning Conjunctive Normal Form, if it is a conjunction of disjunction of literals (a literal is a propositional variable or its negation). Hence, a CNF is a formula of the form: $K_1\wedge K_2\wedge \mathrm{\dots }\wedge K_n$, where each $K_i$ is of the form $l_{i1}\vee l_{i2}\vee \mathrm{\dots }\vee l_{im}$ for literals $l_{ij}$ and some $m$ (which can vary for each $K_i$).

Example: $(x\vee y\vee \mathrm{\neg }z)\wedge (y\vee \mathrm{\neg }w\vee \mathrm{\neg }u)\wedge (x\vee v)$.