noun
swimming trunks; swim trunks
Wasei-eigo from English 'swimming pants'; refers to men's or unisex swimwear bottoms, not full-length pants.
wasei-eigo (Japanese-coined English), from swimming pants
プールに行く前に、新しいスイミングパンツを買った。
Before going to the pool, I bought new swimming trunks.
彼は青いスイミングパンツをはいている。
He is wearing blue swim trunks.