The term ‘vice versa’ is not classified as a colloquialism. It comes from Latin and is used to indicate that the reciprocal of a statement is also applicable. For example, if you say, ‘He loves her, and vice versa,’ it means that she loves him too.
While it’s commonly used in casual speech, it retains its formal roots and usage in written language. Therefore, though it may often appear in everyday conversation, its use is acceptable in more formal contexts as well.