on duty

Idioms  

1. At one's post, at work, as in The new nurse was on duty that evening, or The watchman was fired because he was drunk on duty. [Mid-1600s] The antonym, off duty, means “not engaged in one's work,” as in Captain Smith was much more amiable when he was off duty. [Mid-1800s]

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Example Sentences

On the night of the attack, she was reportedly turned away by a nearby private clinic, which said it did not handle emergencies and had no doctor on duty.

From BBC • Jun. 22, 2026

According to family lore, my policeman grandfather was on duty at Yankee Stadium on the evening of June 22, 1938, when he started chatting with a man from out of town.

From The Wall Street Journal • Jun. 18, 2026

Around 4,000 Swiss troops will be on duty on land, on Lake Geneva and in the air, coordinating with the French military.

From Barron's • Jun. 14, 2026

But after confirming that her fetus still had heart tones, the OB-GYN on duty, Dr. Britte Smith, said she couldn’t induce yet.

From Salon • May 27, 2026

Moneywort, the sentry on duty, was peering uneasily out of the mouth of the hole, but turned as he approached.

From "Watership Down: A Novel" by Richard Adams