Definition of 'round the clock/around the clock' If something is done round the clock or around the clock, it is done all day and all night without stopping. Rescue services have been working round the clock to free stranded motorists. We can't afford to give you around-the-clock protection.

If a patient needs round-the-clock care in the hospital, they'll have nurses checking on them nonstop, day and night. Round-the-clock dates from the 1940s and was first used to describe air raids during World War II.

all day and all night without stopping: They're working around the clock to get it done. around-the-clock news coverage.

ATC stands for "around-the-clock." Around-the-clock (ATC) medication is defined as medication that is given at regularly scheduled intervals throughout the day. 1 This can include a dose during the night. Around-the-clock dosing is common for opioid medication to manage pain.