What Is a Bathing Suit? | Swimwear Basics Explained

A bathing suit is a garment worn for swimming, and in American English the term is synonymous with swimsuit.

If you’ve been shopping for swimwear, you’ve probably seen “bathing suit,” “swimsuit,” and “swimwear” used interchangeably. That’s because they refer to the same thing. A bathing suit covers the body for water activities, whether that’s a one-piece, a bikini, or a pair of trunks. The term is linguistic rather than a distinct product category, so there are no separate technical specs or versions to worry about.

The Simple Definition

Cambridge English Dictionary defines a bathing suit as “a piece of clothing that you wear for swimming.” Merriam-Webster offers an even shorter version: “swimsuit.” Both definitions point to the same conclusion—there’s no functional difference between a bathing suit and a swimsuit in everyday American usage.

The word “bathing” carries a slightly old-fashioned tone in some regions, but it remains common across the United States. You’ll hear it at pools, beaches, and water parks, and no one will look at you sideways for using it.

Types of Bathing Suits

Because the term is broad, it covers every style of swimwear worn today. The main categories include:

• One-piece suits — a single garment covering the torso, popular for swimming laps and active water sports.
• Bikinis — a two-piece set with a top and bottoms, widely worn for recreation and sunbathing.
• Tankinis — a two-piece with a longer top that covers more of the torso than a bikini.
• Boardshorts and swim trunks — loose-fitting shorts worn by men and women for swimming and beach activities.
• Swim briefs — form-fitting bottoms worn by competitive swimmers.

All of these count as bathing suits. The term doesn’t imply a single style or gender, which is a point many people get wrong.

Regional Usage and Related Terms

Dictionaries note that “bathing suit” is primarily North American English. In the United Kingdom and Australia, you’re more likely to hear “swimming costume” or “cossie,” while “swimsuit” works nearly everywhere. Major dictionaries list bathing costume, swimming costume, swimsuit, and swimwear as synonyms or near-synonyms.

Wikipedia’s entry on swimsuits confirms the overlap, treating the terms as describing the same category of clothing. Whether you pack a one-piece or trunks, you’re bringing a bathing suit.

Common Mistakes People Make

The most frequent error is treating “bathing suit” and “swimsuit” as separate product categories. They aren’t. A store shelf labeled “swimwear” contains the same items you’d call bathing suits. Wikipedia’s swimsuit article traces this history, showing how the terms have always described the same garments.

Another mistake is assuming the term only refers to women’s swimwear. Trunks, boardshorts, and swim briefs for men all fall under the bathing suit umbrella. The word is gender-neutral and applies to any garment designed for swimming.

How to Choose the Right Bathing Suit

Since a bathing suit is just swimwear, choosing one comes down to fit, activity, and personal comfort. If you’re swimming laps, a one-piece or swim briefs reduce drag. For lounging and casual beach time, boardshorts or bikinis offer more flexibility. Fabric matters too—most suits use nylon or polyester blends that dry quickly and resist chlorine and saltwater.

Sizing varies across brands, so check each manufacturer’s fit guide before ordering. If you’re shopping for bottoms specifically, our roundup of the best bathing suit bottoms covers top-rated styles for different body types and activities. A suit that fits well stays comfortable whether you’re swimming or just soaking up the sun.

The practical takeaway: don’t overthink the terminology. “Bathing suit,” “swimsuit,” and “swimwear” all describe the same clothing, and the best choice is the one that fits well and suits how you plan to use it.