hidden motive
noun phraseUK /ˈhɪd.ən ˈməʊ.tɪv/
US /ˈhɪd.ən ˈmoʊ.tɪv/
A secret reason for doing something that you do not tell others about.
She was extra nice to the new kid, but I think she had a hidden motive.
OTHER MEANINGS
2. A reason kept private to avoid suspicion or trouble.
He offered to help with the project, but his hidden motive was to get extra credit.
3. An unstated goal behind a kind or helpful action.
The company's donation seemed generous, but it had a hidden motive: free advertising.
4. A secret plan that drives someone's behavior.
The detective suspected a hidden motive behind the sudden friendship.