mon‧i‧tor1 S3 W3 [transitive]
to carefully watch and check a situation in order to see how it changes over a period of time:
Patients who are given the new drug will be asked to monitor their progress.
The government is monitoring the situation closely.
The temperature is carefully monitored.
monitor what/how etc➔ see usage note control2
We need a better system for monitoring what is going on.
to secretly listen to other people's telephone calls, foreign radio broadcasts etc:
He suspected that his phone calls were being monitored.