Halve
Halve is a verb meaning either (1) to divide into two equal portions or parts, or (2) to lessen or reduce by half. Halve doesn’t work as a noun—though halves, with an s, is the standard plural of half.
Incidentally, halve is usually pronounced the same as have; the l is silent.
Examples
Here are a few examples of the verb halve and its corresponding gerund and participles used well:
But people familiar with the plan say that one hallmark is a proposal to roughly halve the number of board members from the current 27. [Wall Street Journal]
The Pakistani government has caved in to public anger and a coalition party ultimatum by halving a fuel price rise. [BBC News]
A smattering of University of Canterbury courses will resume next week, while the institute’s term break has been halved. [Stuff.co.nz]
Mr. Quagliata halves the brussels sprouts, and cuts the butternut squash and the apples into asymmetrical chunks. [New York Times]
And in these examples, halves is the plural of half:
Squeeze the juice from the lemon halves into the water, then add the rinds to the pot. [Miami Herald]
The club also faces a secondary charge that it was responsible for both the first and second halves at Camp Nou starting late. [Guardian]