Superlative form of rotten: most rotten.(adjective)
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Use "rottenest" in a sentence
"Her daddy think that they doin’ to her but he don’t see that Sinestra the rottenest apple in the barrel."
"I've always noticed it's the fastidious, la-de-da ones that turn out the rottenest."
"The friends had first met when Watson was part of the 406, the department that did some of the rottenest jobs in the mill, such as cleaning out the grease pits and sumps."