advertisement for Wilson & Co.’s overcoats
from Lloyd’s Weekly Newspaper (London) – 6th November 1898
The verb to buttonhole has two meanings: 1) to buttonhole a garment means to make buttonholes in a garment; 2) to buttonhole someone means to detain someone in conversation against their will.
In its second sense, it is an altered form of to button-hold someone, meaning to take hold of someone by a button and detain them in conversation against their will.
The earliest instance of to button-hold that I have found is from a letter to Clement Tudway, M.P. for the City of Wells, in Somerset, published in The Bath Chronicle (Bath, Somerset) on 13th February 1783:
In conversation between you and some friends to the bill, you spoke so unequivocally of not opposing it, that men of plain sense and integrity, unacquainted with your character, were induced to believe you; true it is you did not long deceive them, for tho’ you affected at the meeting the most childish prevarication and ambiguity, yet when your whispers came to be blown abroad by your button-held confidants, every body saw in you a strenuous opposer.
The earliest occurrence of the verb to button-hole that I have found is from The Dublin Evening Post (Dublin, Ireland) of 16th May 1846:
New Orleans, April 21, 1846.—Upon the arrival of the Alabama, from Galveston, about five yesterday afternoon, the city was thrown into a feverish state of excitement on learning that she had spoken to the U.S. steamer, Colonel Harney, direct from the Brassos de St. Jago, and that she had reported that Mexico had declared war against the United States, and that our naval force had, in consequence, blockaded her ports. The rumour obtained very general credit, and nothing else was talked of for hours and hours, and the arrival of the Colonel Harney was anxiously looked for. About eleven o’clock she came crawling along, and the newspaper people soon boarded and button-holed every man or boy who would be likely to know anything at all about passing events.
Interestingly, on 19th May of that year, The Limerick Reporter (Limerick, Ireland) used the form button-held when announcing the same event:
The newspaper people […] button-held every man or boy who would be likely to know anything at all about passing events.
Likewise, the author of an article titled Buttons, published in the weekly All the Year Round on 28th June 1862, used both to buttonhole and to button-hold:
And there is the man who is button-holed, or held, poor wretch! and must listen to half an hour’s harangue about nothing interesting, while his friends are waiting dinner, or his wife is sitting in her diamonds and opera cloak, sullenly expecting his escort. The man who button-holes another is a ruffian, not fit for civilised society, and ought to go out to the long-winded savages who have not yet learnt that brevity is the soul of wit.
This shows that the verb to button-hold and its altered form to button-hole were both in usage at that time. The reason for this alteration is probably that in spoken language button-hold was mistaken for a past tense or a past participle, which led to the verb to button-hole being invented in order to match the original error.
Robert Hendrickson gave a ludicrous explanation in The Facts On File Encyclopedia of Word and Phrase Origins (4th edition – New York, 2008):
In those days [= the early 19th century] men’s coats had buttons all the way up to the neck, including one on the lapel that could be buttoned in cold weather. When fashion decreed that upper buttons be eliminated, button-holders didn’t suddenly reform. Instead, they began grabbing people by the buttonholes designers (for no good reason) left on the lapels and the phrase [= ‘to button-hold’] became ‘to buttonhole’.
It is typical of folk etymologies that stories have to be made up in order to support false theories.