hiddenreason
nounUK /ˌhɪd.ən ˈriː.zən/
US /ˌhɪd.ən ˈriː.zən/
A hidden reason is a secret reason that someone does not tell you.
She was extra nice to the new kid, but there was a hidden reason: she wanted his help with homework.
OTHER MEANINGS
2. A reason that is not easy to see or notice at first.
The hidden reason for the puddle was a tiny crack in the pipe.
3. A reason someone keeps to themselves on purpose.
He smiled at the surprise party, but his hidden reason for smiling was that he already knew about it.
4. The real cause behind something that seems different on the outside.
The hidden reason the plant wilted was too much water, not too little.