Pants
mid 19th century: abbreviation of pantaloons (see pantaloon).
wiktionary
Shortened from pantaloons(“trousers”). (This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium. Particularly: “The rubbish sense is rather odd -- how did this develop?”)
pants (third-person singular simple present pantses, present participle pantsing, simple past and past participle pantsed)
pants
pants
etymonline
pants (n.)
"trousers, drawers," 1840, see pantaloons. The word was limited to vulgar and commercial use at first.
I leave the broadcloth,—coats and all the rest,—
The dangerous waistcoat, called by cockneys "vest,"
The things named "pants" in certain documents,
A word not made for gentlemen, but "gents";
[Oliver Wendell Holmes, "Urania: A Rhymed Lesson," 1846]
Colloquial singular pant is attested from 1893. To wear the pants "be the dominant member of a household" is by 1931. To do something by the seat of (one's) pants "by human instinct" is from 1942, originally of pilots, perhaps with some notion of being able to sense the condition and situation of the plane by engine vibrations, etc. To be caught with (one's) pants down "discovered in an embarrassing condition" is from 1932.
