What for? Definition 1 of 2Pro Tip 1/3Emotion Intensifier Used to emphasize emotion, often out of exasperation or confusion. You're moving to another country, what for?! Pro Tip 2/3Conversational Cue Signals you want more information about the reasons behind an action or decision. You're quitting your job, what for? Pro Tip 3/3Genuine Inquiry Shows real curiosity, not a rhetorical question. You're learning sign language, what for? That's interesting.