noun, noun which may take the genitive case particle 'no', noun or participle which takes 'suru', intransitive verb
being on duty; being on watch
Refers to the state of being on duty, especially for night shifts or emergency standby in hospitals, factories, or security roles. Often used with する to mean 'to be on duty'.
今夜は当直なので、家に帰れません。
I'm on duty tonight, so I can't go home.
当直
Please call the doctor on duty.
noun
Refers to the person who is on duty, especially in a professional setting like a hospital or security post. Often used with の to modify another noun.
当直はまだ来ていません。
The person on duty hasn't arrived yet.