You know how we often use hyphens in multiple-word descriptions? I actually just used one in that last sentence.
Many writers use a hyphen even if the description follows the noun it’s describing, though the Chicago Manual of Style tells us this is usually unnecessary even when such compounds are hyphenated in Merriam-Webster. Here’s an example: “Stephen King is well-known for his horror writing.” When I’m editing, I typically leave this up to author preference.
Some common words that can be left open in most descriptions are “less,” “least,” “more,” and “most.”
Following this advice, you would write “That is the most abhorrent Christmas sweater at this entire party” or “That Christmas sweater is the most abhorrent at this entire party.”
This way of thinking also applies if you’re using a description that ends with one of these words. Here’s an example: “Minnesota is the northernmost state of the forty-eight contiguous states.” It doesn’t need a hyphen.
Just something to keep in mind while writing or editing!
Timothy