Superlative form of speedy: most speedy.(adjective)
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Use "speediest" in a sentence
"One of the speediest is running back/defensive back Shyrone Carey, who signed with Tennessee last year but was academically ineligible and never enrolled."
"With yesterday's release of the newest Chrome Beta, Google is pumping up the speed -- impressive for a browser that's already known as the speediest around."
"Mr. Carrabba said that by offering an all-cash deal, it would be the "speediest" way to get a deal done in Canada."