* Cruelty: This is the noun form of "cruel," meaning the quality or state of being cruel.
* Cruelly: This is the adverb form of "cruel," meaning in a cruel manner.
* Crueler: This is the comparative form of "cruel," meaning more cruel.
* Cruelest: This is the superlative form of "cruel," meaning most cruel.
While you can't add suffixes directly to "cruel" to create new adjectives, these related words offer different ways to express the concept of cruelty.