Q: I was watching the BBC show Blandings when the Earl was discomforted by an American’s use of “pants,” until it was explained that the reference was to trousers, not underpants. Is the meaning of “pants” still different in the US and the UK? If so, when did it diverge?
A: Yes, “pants” is one of those words that distinguish American from British usage. The usual meaning is “underpants” in the UK and “trousers” in the US. However, a secondary meaning in the US is “underpants.”
The word first appeared in the US in the early 1800s as a clipped version of “pantaloons,” close-fitting men’s breeches common in the 19th century.
The longer term, which showed up in its trousers sense in the 17th century, is ultimately derived from Pantalone, a silly old man in Italian commedia dell’arte whose thin legs were encased in long tight trousers, according to John Ayto’s Dictionary of Word Origins.
The earliest example for “pants” in the Oxford English Dictionary is from an 1835 issue of the Southern Literary Messenger: “In walked my friend—pumps and tight pants on—white gloves and perfumed handkerchief.”
In American English, according to the OED, “pants” originally referred to men’s trousers, but in the 20th century the term “extended to include those worn by both men and women.”
In the late 1800s, “pants” showed up in British usage as “underpants.” Ayto suggests that this meaning was “perhaps influenced by pantalets, a 19th-century diminutive denoting ‘women’s long frilly drawers.’ ”
The earliest OED example for the underwear sense of the word is from the Nov. 8, 1880, issue of the Daily News in London: “Pants and shirts sell rather freely, and jerseys are still in request.”
The OED‘s latest citation is from a 1999 issue of Watt’s On, the student newspaper at Heriot-Watt University in Edinburgh, Scotland: “The University seems to be asking us to choose between wearing no underwear … and wearing damp pants.”
While the OED says this is “chiefly” a British usage, it does occur in American English, as we mentioned. Many standard dictionaries in the US recognize “underpants” as a secondary sense. And Pat recalls that “pants” meant underwear and trousers when she was growing up in Iowa.
The American novelist Thomas Sterling uses the word both ways in his thriller The House Without a Door (1950), as seen in these two examples:
(1) “She chose her blue underwear, trimmed with sand-colored lace, which she had ordered from an advertisement. She laid the pants and brassière on her bed and placed a plain blue slip beside them.”
(2) “He walked down the stairs, struggling for change in his pants pocket.”
The OED says “pants” also has the slang sense of “nonsense” in British English, especially in the expressions “a pile of pants” and “a load of pants.”
The first citation for the slang usage is from the Sept. 22, 1994, issue of the Guardian: “It’s all a bit embarrassing because Mayo (catchphrase: ‘It’s a pile of pants!’) fails to recognise her at first.”
The word “pants” is used colloquially in various other expressions. Here are some cited in the OED and the dates of their earliest examples:
“to wear (also put on) the pants: to be the dominant member of a household, relationship, partnership, etc.,” 1898.
“to be caught with one’s pants down: to be surprised in an embarrassing situation; to be caught off guard,” 1922.
“to beat (also bore, scare, etc.) the pants off (a person): to beat (bore, scare, etc.) completely, utterly, or beyond the point of endurance,” 1925.
“to keep one’s pants on: to keep calm,” 1928.
“to get into someone’s pants: to have sexual intercourse with (a person),” 1937
“by the seat of one’s pants: by instinct and experience rather than logic, expert knowledge, or technical aid,” 1938.
As for Blandings, we haven’t watched the BBC series. But we’re big fans of P. G. Wodehouse’s novels and stories, so we’re familiar with Lord Emsworth, the Empress (his prize pig), and the other residents of Blandings Castle.
from Grammarphobia http://www.grammarphobia.com/blog/2016/12/pants-2.html