under-the-table definition by American Heritage Dictionary
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
adverb & adj.
Not straightforward; secret or underhand.
under-the-table - Phrases/Idioms
In secret, as in They paid her under the table so as to avoid taxes. This term alludes to money being passed under a table in some shady transaction, such as a bribe. [Mid-1900s] Also see under the counter.
Variant of under-the-counter
Informal done, sold, given, etc. secretly in an unlawful or unethical way