Learn English – Is “horrorest” a correct English word

This isn't an exhaustive list, but let me give it the old college try. In english, the following suffixes are considered adjective-forming:

Relational Family

All the members of this family mean of or pertaining to. Some have a different scope than others.

• -al (Fungal, Cranial)
• -an/-ian/-n (Roman, American, Historian)
• -ar (Scalar, Modular)
• -ic (Acidic, Idyllic)
• -id (Perseid)
• -ese/-ish :: of or pertaining to characteristics of a location, its people, and the language they use (Japanese, Maltese, British, English, Irish)
• -ish/-y :: somewhat, about or approximately when used with numbers, typical or similar to (Sciencey, Girlish, Tennish, Twentyish)
• -ous/-ious/-atous (Bulbous, Courageous)
• -otic (Eukaryotic, Symbiotic)

Of Similar Form To, But Not the Same As

• -oid (Humanoid, Alkaloid)
• -like (Lifelike, Childlike)

Others

• -th :: ordinal (Fourth, Fifth, Sixth, Seventh, Eighth, Ninth)

Best is used all the time when talking about two things or people.

"The best 1998 science fiction movie about people fornicating with chickens inside the Astrodome is Glubaba, which is way better than Raise your right arm.

Usage Note: According to a traditional rule of grammar, better, not best, should be used in comparisons between two things: Which house of Congress has the better attendance record? This rule is often ignored in practice, but it still has many devoted adherents. In certain fixed expressions, however, best is used idiomatically for comparisons between two: Put your best foot forward. May the best team win!