monitor noun

1 television/computer screen

ADJ. colour | CCTV, computer, television/TV, video

PREP. on a/the ~ The security staff can see all the outside of the building on their CCTV monitors.

2 machine that records/checks sth

ADJ. foetal, heart, oxygen, pulse, radiation

MONITOR + VERB detect sth | show sth The heart monitor shows the strength of your pulse.

3 sb who checks sth is done fairly/properly

ADJ. EU, UN UN monitors declared the referendum fair. | school | health, peace