the.com/swish

means To move with a soft rushing sound, or to describe something elegant and stylish; in basketball, a shot that drops cleanly through the net without touching the rim.

from An imitative word — born from the sound itself, the soft hiss of fabric or air or a switch cutting through space. English is full of these 'echoic' coinages (swoosh, whoosh, hush), and 'swish' joined them a few centuries back. The fashionable sense of 'swish' meaning posh or stylish is later British slang, perhaps borrowing the swish of expensive skirts and curtains; the basketball sense is newer still, American, naming the near-silent perfection of a clean shot.