There are 24 hours in a day.
How many hours' sleep do you need?
I'll be back in an hour's/two hours' time (= after one/two hours).
Our opening hours are from 8.00 to 6.00.
work long, regular, unsocial, etc. hours
at all hours (of the day and night) C1 disapproving
Thesaurus: synonyms and related words