Superlative form of coarse: most coarse.(adjective)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "coarsest" in a sentence
"Men of deserved renown, and peerless women, lived upon what we should now call the coarsest fare, and paced the rushes in their rooms with as high, or as contented thoughts, as their better-fed and better-clothed descendants can boast of."
"While others in the Order called the immortals miscreats, short for miscreations, Declan often used the term detrus, the coarsest word they had for them."
"Feelings and thoughts than with his coarsest actions."