The clothes that one wears when bathing in the sea or a swimming pool; a swimming costume, bathing suit, swimming trunks or swimsuit.(noun)
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Use "bathing costume" in a sentence
"She took off pullover, shirt, slacks, socks and vest behind rocks, and, in the one-piece sea-green bathing costume she had put on underneath the rest of her clothing, she went cautiously seawards, wearing her rope-soled shoes."