Superlative form of arrant: most arrant.(adjective)
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Use "arrantest" in a sentence
"The Lord above knows who it was told her: for I am the arrantest villain that ever walked upon two legs if ever it came out of my mouth."
"The liquor soon mounted into their heads, as it generally does even with the arrantest topers newly landed from sea, and they began capering about most obstreperously."
"He slyly adds: "They were like enough to do it, for they were the arrantest apes in their religion I ever read of.""