What does cossie mean?
"Cossie" is an affectionate, informal noun for a swimming costume or swimsuit, heard mainly in Britain and Australia. It is a clipped, diminutive form of the older word "costume," which in Victorian times referred broadly to garments worn for particular activities — including bathing. Today the word carries a breezy, casual tone: nobody wears a cossie to a board meeting, but plenty of people pack one for the beach, the pool, or a hot summer's day in the garden. In Australia it is one of several beloved regional terms for swimwear, alongside "bathers" in South Australia and "togs" in Queensland, while Britons use it interchangeably with the fuller "swimming costume." The plural is "cossies." Because it is so firmly conversational, the word rarely appears in formal writing, yet it remains a warm, instantly recognizable marker of everyday seaside and poolside life in the countries where it thrives.
nounAn informal term for a swimming costume or swimsuit, used chiefly in British and Australian English.
- An informal British or Australian word for a swimsuit or swimming costume.
"Don't forget to pack your cossie — the hotel pool opens at seven."
"She bought a new cossie before the family holiday to Cornwall."
"It was so hot we all changed into our cossies and ran through the sprinkler."
Regular plural formation; used when referring to multiple swimsuits or to swimwear collectively.
"The shop sells cossies in every colour imaginable."
Australians loved this word so much that "cossie" even beat out formal terms in national surveys about beachwear vocabulary — proof that a two-syllable nickname can outswim its full-length parent.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cossie
"Cossie" arose as an informal clipping of "swimming costume," with the -ie suffix added in the manner of many affectionate English diminutives. The parent word "costume" entered English from French in the early eighteenth century, ultimately tracing back through Italian "costume" to Latin "consuetudo," meaning custom or habit. The shortened form became established in British and Australian colloquial speech during the twentieth century, and it survives today as a distinctly informal synonym for swimsuit in those varieties of English.
How cossie is actually used
Register: distinctly informal and colloquial. Most strongly associated with British English and especially Australian English, where it competes with regional alternatives like "bathers" (South Australia) and "togs" (Queensland). Rarely used in North America, where "swimsuit" or "suit" predominates.
Easily confused with cossie
"Cozzie" is simply a variant spelling of the same word, with no difference in meaning.
"Cosy" (or "cozy") means warm and comfortable, whereas a "cossie" is an item of swimwear; they differ by one letter but are unrelated in meaning.