Cases of word usage

1) the act, state, of detaining or being detained, e.g. keeping a pupil in school after ordinary hours as a punishment (detention)

2) a senior pupil given duties in a school; a person, apparatus, that listens to or watches foreign radio and television programmes; a screen on which information can be seen (monitor)

3) a private teacher of a single pupil or a very small class; (GB) a university teacher who advises and guides a student (tutor)