set one's watch by someone

English

Verb

set one's watch by someone (third-person singular simple present sets one's watch by someone, present participle setting one's watch by someone, simple past and past participle set one's watch by someone)

1. To know what time it is by observing a very punctual and reliable person going about their regular routine.

Usage notes

• Used in hypothetical constructions with can, could, etc. to describe a person as being very punctual: "You could set your watch by him".

See also

• like clockwork