Or just (flip .), which also allows ((flip .) .) etc. for further flips.
In Smullyan's "To Mock a Mockingbird", these combinators are described as "cardinal combinator once/twice/etc. removed", where the cardinal combinator itself defines flip.
In Smullyan's "To Mock a Mockingbird", these combinators are described as "cardinal combinator once/twice/etc. removed", where the cardinal combinator itself defines flip.