From Longman Dictionary of Contemporary Englishsailor suitˈsailor suit noun [countable] DCCa blue and white suit that looks like an old-fashioned sailor’s uniform, worn by small boys
Examples from the Corpus
sailor suit• He put on a sailor suit for real during a stint in the Navy.• He still wears a sailor suit, the cowlick at his hairline gives his forelock a life of its own.• He was in his sailor suit, dressed for church.• Incredible deltoids, biceps, buttocks, and thighs outlined and simultaneously gripped by the tight cut of his sailor suit.• Not from his cradle of course, since his sailor suit days.• Lily, I've on my new sailor suit. 