book on
In real, traceable use. Part of the curated seed collection; community review is coming.
Meaning · English
To register (for duty).
Where it’s used:
Used
American English
Examples
Having woken at 0900 the previous morning, he had not slept during the day and had already been awake for 11 hours when he booked on.
Usage example from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30)
Sources & notes
Adapted from English Wiktionary (CC BY-SA 4.0, retrieved 2026-07-30 via kaikki.org).
Common questions
What does “book on” mean?
To register (for duty).
Is “book on” formal or informal?
No register label has been reviewed yet — treat it as neutral and check the usage notes above.