an often duplicitously undisclosed plan or motive.
The Hidden Histories Of “Humpty Dumpty,” “London Bridge,” And “Ring Around The Rosie”These hidden stories behind these three popular nursery rhymes may not be well known but they certainly make songs like "Humpty Dumpty" a little more interesting.
Origin of hidden agenda
First recorded in 1985–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for hidden agenda
a hidden motive or intention behind an overt action, policy, etc
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012