Learner's definition of DECEPTION
1 [noncount] : the act of making someone believe something that is not true: the act of deceiving someone
She accuses the company of willful deception in its advertising.
The article describes the government's use of deception [=deceit] to gain public support for the program.
She practiced deception on her unsuspecting clients. [=she deceived them]
2 [count] : an act or statement intended to make people believe something that is not true
His many deceptions did not become known until years after he died.
It was a misunderstanding on her part, not a deliberate deception on his (part). [=he didn't try to deceive her or lie to her]
a clever deception [=trick]