ずぼん

Etymology 1
Onomatopoeia. The zu portion indicates something rubbing or sliding (compare verb suru, “to rub or slide”), and the bon portion indicates something bumping to a stop or softly popping into or out of place.

This term appears in print in 1860, raising the possibility that the onomatopoeia sense arose from the borrowed noun and the action of putting on a pair of trousers. The initial zu portion does not historically refer to rubbing or sliding, but instead more commonly carries negative connotations of or. Alternatively, this is a colloquial term, and it may have been a dialect term, and thus it might be older than its history in print.

Adverb

 * 1) * 1860, 七偏人 (Shichi Henjin, “Seven Eccentrics”), volume 4:
 * 1) * 1860, 七偏人 (Shichi Henjin, “Seven Eccentrics”), volume 4:

Usage notes
Takes the particle, as in the quoted example above.

Etymology 2
Alternative form of. See that entry for more detail.