countable a period of time that consists of 60 minutes. 30 minutes is usually called half an hour, 15 minutes can be called a quarter of an hour, and 45 minutes can be called three-quarters of an hourevery hour: She checked on the children every hour.
an hour ago: He left about an hour ago.
an hour of something: After an hour of arguing, he agreed.
an hour’s sleep/exercise/practice etc: Why don’t you get an hour’s sleep?
for an hour: I’ve been waiting for over an hour.
take an hour to do something: This dish takes about an hour to cook.
it takes an hour to do something: It takes nearly an hour to get there by bus.
in an hour/an hour’s time: I can be there in an hour.