Used in indicating a thing with two roles, functions, or natures, or a thing that has changed from one to another.

“He built a bus-cum-greenhouse that made a bold statement, but the plants in it didn't live very long.”

Used in indicating a thing with two or more roles, functions, or natures, or a thing that has changed from one to another.

“But instead of being a salesperson cum barista cum waitress merely serving the wordsmiths, I'm one of them, reading her latest baby out loud.”