The Stacks project

Definition 41.21.4. Let $X$ be a locally Noetherian scheme. A normal crossings divisor on $X$ is an effective Cartier divisor $D \subset X$ such that for every $p \in D$ there exists an étale morphism $U \to X$ with $p$ in the image and $D \times _ X U$ a strict normal crossings divisor on $U$.