This is the 1990th most frequent Catalan word.
retenir
To retain or to hold back.
Here, 'retenir' means to 'retain' or 'keep' information in one's memory.
Vaig haver de retenir la informació per a l'examen.
I had to retain the information for the exam.
In this context, 'retenir' means to 'detain' or 'hold someone back' for further action or interrogation.
La policia va retenir el sospitós per interrogar-lo.
The police detained the suspect for questioning.
Here, 'retenir' is used to mean 'hold back' or 'restrain' an emotion or reaction.