Bikini/bɪˈkiːni/ Definition 1 of 3Pro Tip 1/3Casual Wear Bikinis are casual wear, suitable for the beach or pool, not formal events. She packed bikinis for the pool party. Pro Tip 2/3Fashion Variation Bikinis come in many styles and patterns; choose one based on personal preference and comfort. She preferred a high-waisted bikini for added comfort. Pro Tip 3/3Mix and Match Bikini tops and bottoms are often sold separately, allowing for creative combinations. She mixed a striped bikini top with a solid blue bottom.