on the hour

At every hour exactly; one o'clock, two o'clock, and so on. For example, The shuttle to New York departs on the hour. An extension of this idiom is every hour on the hour, meaning every time the clock's big hand reaches twelve, as in The bus passes by the house every hour on the hour.

Words nearby on the hour

on the go, on the heels of, on the hill, on the horizon, on the horns of a dilemma, on the hour, on the house, on the in, be, on the increase, on the inside, on the job