Longman Dictionary of Contemporary English
Wiktionary
n. (context chiefly British rather dated English) The clothes that one wears when bathing in the sea or a swimming pool, especially the one-piece garment worn by women and girls; a swimming costume, bathing suit, swimming trunks or swimsuit.
WordNet
n. tight fitting garment worn for swimming [syn: swimsuit, bathing suit, swimming costume]
Usage examples of "bathing costume".
She ignored Isabella's howls of protest and stripped off her bathing costume.
He appeared to be one of those men who can look after themselves in the water only when they are in bathing costume.
A group in bathing costume, arms round one another, laughing by the seaside.
I felt small pangs of hunger starting up, changed out of my bathing costume and headed for home again.
One of them had on what seemed to be a gold satin bathing costume with a matching top hat.