Superlative form of slender: most slender.(adjective)
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Use "slenderest" in a sentence
"The statement below could be, lets say could be called slenderest, you need to check your fats and educate your self."
"It seemed to partake of her soul, to have analogous attributes, and to link it to life with the slenderest of chains."
"As John P.A. Ioannidis, a professor of medicine at Stanford, argued in his provocative 2005 paper, "Why Most Published Research Findings Are False," just because a study can claim the slenderest of statistical significance doesn't mean that the finding can be repeated in later research."