Half is the noun or adjective, one of two equal parts, as in half the class or eat half a sandwich. Halve is the verb, the action of dividing something into two halves, or of cutting an amount down by fifty per cent, as in halve the recipe. If you are naming the part, use half; if you are doing something to create it, use halve.
The core difference
Half names one of two equal parts; halve is the act of dividing something into two, or of cutting an amount in two.
- half — one of two equal parts into which something is divided: cut the apple into two halves.
- halve — to divide something into two halves, or to reduce it to half its amount: halve the onion before slicing it.
- half — also works as an adverb meaning partially: he was half asleep during the lecture.
How to tell them apart
Half is one of the oldest words in English, going back to Old English healf, and it does double duty as a noun (a half), an adjective (half a sandwich) and an adverb (half finished). Halve is the verb built from it, and it covers two related actions: physically cutting something into two equal pieces, and more figuratively cutting a quantity down to fifty per cent, as when a company halves its costs.
The spelling trips people up because halve keeps a silent e that half does not have, echoing other verb-noun pairs such as shelf and shelve.
