A separatrix is a punctuation mark that separates alternative words, like "either/or" and "he/she/they."
You probably call a separatrix a slash, but other terms for this mark are solidus and virgule. It's used for fractions in math, and to indicate dates like 10/14/2025. A separatrix is also shorthand for the word or: "Do you like me? Yes/No." In proofreading, this mark indicates a replacement word or sentence for text that's been crossed out. Separatrix has a Latin root that means "to pull apart or separate."