Meaning of “half” - Learner’s Dictionary

half

noun, determiner us uk /hɑːf/ plural halves
Extra Examples
Mix in half the butter and keep the remaining 50g for later.Sales for the first half of this year fell just short of the target.The southern half of the country will have wet weather.We'd walked half a mile uphill.He only got half the answers right.

A2 [ C, U ] one of two equal parts of something; 1/2:

Rice is eaten by half of the world's population.
Cut the lemons into halves.
It'll take half an hour to get there.
Jenny lived in Beijing for a year and a half.
break/cut/split sth in half

B1 to divide something into two equal parts:

Divide the dough in half and roll it out into two circles.
decrease/increase, etc sth by half

to make something smaller/larger, etc by half its size:

The drug reduces the risk of stroke by half.
half past one/two/three, etc mainly UK

A1 30 minutes past one o'clock/two o'clock/three o'clock, etc:

We got back to our hotel at half past seven.
half one/two/three, etc UK informal

A1 30 minutes past one o'clock/two o'clock/three o'clock, etc:

"What time does it start?" "About half six."

(Definition of “half noun, determiner” from the Cambridge Learner’s Dictionary © Cambridge University Press)