the.com/fad

means A craze that a lot of people suddenly take up with enthusiasm, and that fades out almost as fast as it arrived.

from Genuinely uncertain. 'Fad' surfaced in the 1800s as a shortened slangy word, possibly linked to the older dialect word 'fidfad,' meaning a fussy person obsessed with trifles — but the trail goes cold fast, and no one can prove a clean ancestor. It's one of those words that arrived looking like an abbreviation of something, without ever confirming what.