Most swift or fast-moving; quickest; most nimble or agile.
Superlative form of 'fleet' (adjective), formed with the '-est' suffix following the standard English pattern for superlatives of short adjectives, emphasizing the ultimate degree of swiftness.
The superlative 'fleetest' appears in classical poetry because it rhymes beautifully with words like 'meet' and 'feet'—sound influenced which adjectives English speakers kept alive in elevated language.
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