pro-rated

[mato]

'a pro-rated holiday entitlement of...'

obviously pro rata is an adjective or an adverb, but can one pro rate something?

[claricebeansmum]

Don't think so..

"Holiday entitlement is pro rata"

Pro rata is Latin so you can't just add "d" on the end.

[Bink]

Strictly, no ... but for me this falls into life being too short to stuff a pedantic mushroom territory. It works, it's useful, everyone knows what you mean (and that you are stretching the grammar) - it's not so much an error as a liberty.