The phrase "a prohibitively" is correct and usable in written English.
It is typically used to describe something that is excessively high or extreme, making it difficult or impossible to proceed with a particular action or decision.
Example: "The costs of the project were a prohibitively high barrier to entry for many small businesses."
Alternatives: "excessively" or "unduly".
Sign up for the Butt of VICE, delivered to your inbox dAbbott
Or finishing a prohibitively long novel.
Contract lengths were also shortened, and a prohibitively harsh tax was placed on any owners who spent above the cap.
Such a won position is not necessarily one leading to immediate checkmate but one with a prohibitively large advantage of material for White.
Their G.M., Steve Mills — who replaced the savvy Glen Grunwald this past summer — has a prohibitively expensive, yet marginally productive roster and an unpredictably stingy owner.
But his children are still quite young and a gubernatorial campaign would necessitate a prohibitively long leave-of-absence from his medical practice.
While legally allowed to marry, they can do so only after successfully completing realignment surgery, a prohibitively expensive process which costs 200m rupiah (£14,300).
Those included portions presented what the majority said was a prohibitively narrow definition of recess appointment power that would have rendered them difficult for future presidents to use.
The book's introduction nods to why I'm wary of cocktail-drinking as a pastime (other than it being a prohibitively expensive way to get drunk).
The next lesson to learn from last summer was the charge that any challenge to replace a prime minister took a prohibitively lengthy amount of time.
This second phase involves so-called mortgage guarantees and aims to help many more people obtain a mortgage without the need for a prohibitively large deposit.
