Definition of if not
1 —used to talk about the negative result or effect of somethingYou should study. If not, you won't pass the test.
2 —used to express surprise about meeting someone when it is not expectedSo I went to the game and who should I see there if not my old friend Tom!
Love words? Need even more definitions?Merriam-Webster unabridged
Words at Play
Ask the Editors