Also found in: Acronyms.
Written abbreviation of "There is no such thing as a free lunch," meaning nothing is ever really given away for free, so be wary of hidden charges, motives, or agendas. Of course, once you're signed up to the free program, you have to pay for all sorts of extra services to make it even worth using. It's a TINSTAAFL situation if I've ever seen one.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.