Also found in: Acronyms.
An initialism of "let me know." Used primarily in text messages and online communications to ask for another person for tell or inform one (of or about something). I just emailed you my first draft, LMK what you think. A: "Hey, I'm about to cook dinner. LMK when you'll be home." B: "Should be back by 7."
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.