Superlative form of shrewd: most shrewd.(adjective)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "shrewdest" in a sentence
"Once, he was referred to as the shrewdest of business men; now, he was held up to ambitious young tradesmen as a warning wreck, stranded amid the breakers."
""We want to be known as the shrewdest utility regarding energy efficiency," Kilgore said."
"Or was he one of the shrewdest occupants of the White House?"