Also found in: Acronyms.
An initialism of "What do you mean?", used primarily in text messages and online communications. Often spelled in lowercase letters. A: "Why didn't you call me last night?" B: "WDYM?? I tried calling you a dozen times!" A: "Weird, they never came through." Thanks for your help, HamRadioGuy1978, but wdym by "phase shift keying"?
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.