1. (尤指出于政治原因的)拘留，扣押，监禁
Detention is when someone is arrested or put into prison, especially for political reasons.

2. (惩罚顽皮学童的)放学后留校
Detention is a punishment for naughty schoolchildren, who are made to stay at school after the other children have gone home.

1. a punishment in which a student must stay at school after others have gone home

e.g. the detention of tardy pupils

2. a state of being confined (usually for a short time)

e.g. his detention was politically motivated
the prisoner is on hold
he is in the custody of police

Synonym: detainmentholdcustody