It is correct and usable in written English.
You can use it when you want to describe a decrease in size, number, or amount. For example: "After the recession hit, our profits almost halved."
In Ethiopia the figure has dropped from seven to five; in Côte d'Ivoire it has almost halved from its peak; in Botswana it has more than halved.
By 2005 it had almost halved to three, but it then stuck.
While the number of 15- to 34-year-olds using pot has risen or held steady in most countries, in England and Wales it has almost halved (see chart).
In 1999 worldwide revenue reached an all-time high of $27bn; by 2008 it had almost halved, despite the industry's various legal and technological attempts to fight back.
This suggests that while for male migrants who marry a German spouse the propensity to send remittances is roughly a fourth lower, it is almost halved for women.
It is a country that has almost halved its child mortality rates in just ten years, putting it on a par with its wealthier EU neighbour, Hungary.
While cannabis remains the drug of choice, its use has almost halved among the younger generation since 1998.
Its shares have almost halved in value in 12 months and now stand at 933p, down 7% on Thursday.
