The word "swimwear" is a modern English compound noun, formed by directly combining the verb "swim" with the noun "wear." The term "swim" has ancient Germanic roots, tracing back to the Proto-Germanic swimmaną, which itself derives from the Proto-Indo-European root swem(bʰ)-, meaning "to be in motion, to swim." The element "wear," meaning garments, originates from the Old English werian (to clothe), from Proto-Germanic wazjaną, related to the concept of covering the body. The compound logically emerged in the 20th century as specialized clothing for aquatic activities became commonplace, succinctly describing attire specifically for the act of swimming.

Structure: swim (action) + wear (clothing) - swim: From Old English swimman (to move in water). Functional role: Specifies the activity. - wear: From Old English werian (to clothe, to wear). Functional role: Denotes items of clothing.