A swim brief, or racing brief, refers to any briefs style male swimsuit such as those worn in competitive swimming and diving. The popularity of the Australian Speedo (est. 1928) brand racing brief has led to the use of its name to refer to any racing brief, regardless of the maker. Occasionally, the Speedo genericized trademark also applies to square cut swimsuit, but in general the generic term is used in reference to swim briefs. Swim briefs are also referred to as competition briefs, bathers, racer bathers, posing briefs, racing briefs, and colloquially in Australia as "budgie smugglers".

Like underwear briefs, swim briefs feature a V-shape front and a solid back providing form-fitting coverage, though in some countries like Brazil and Japan the "thong-back" Speedo that shows the man's buttocks is also popular. They typically are worn below the lower waist. They are generally secured by thin banding at the upper thighs and either a drawstring around the waist or an elastic waistband. Swim briefs are most often made of a nylon and spandex (Lycra) composite, while some longer lasting suits are made from polyester and still others from other materials. Most swim briefs have a beige or white front lining made of a similar fabric.