Recorded since 1580 in the sense “piece, hunk”. The word luncheon with the same meaning is presumably an extension on the pattern of puncheon (“cask”) and truncheon (“cudgel”). But earliest found forms of luncheon include lunshin and lunching, which are equivalent to lunch + -ing, with the suffix -ing possibly later modified to imitate a French origin. In contrast, the more common sense “light meal” is first attested for luncheon in 1652 and for lunch in 1829, so in this sense the latter is probably a shortening of the former. Lunch is possibly a derivative of lump (as hunch is from hump. See hunch for more), or represents an alteration of nuncheon, from Middle English nonechenche (“light midday meal”) (see nuncheon) and altered by northern English dialect lunch (“hunk of bread or cheese”) (1590), which perhaps is from lump or from Spanish lonja (“a slice”, literally “loin”).
1
A light meal usually eaten around midday, notably when not as main meal of the day.
We made an odd party before the arrival of the Ten, particularly when the Celebrity dropped in for lunch or dinner.1897 December (indicated as 1898), Winston Churchill, chapter V, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd., →OCLC:
US Any small meal, especially one eaten at a social gathering.
After the funeral there was a lunch for those who didn't go to the cemetery.
“Oh, you mustn’t dream of going home without your tea,” cried Anne in distress. “I’ll get it right off—I’ll go and put the tea down this very minute.” “I must go home,” repeated Diana, stupidly but determinedly. “Let me get you a lunch anyhow,” implored Anne. “Let me give you a bit of fruit-cake and some of the cherry preserves. […]”1908, L. M. Montgomery, Anne of Green Gables:
4
Obsolete A thin piece or hunk (of bread, meat, etc.)
Recorded since 1580 in the sense “piece, hunk”. The word luncheon with the same meaning is presumably an extension on the pattern of puncheon (“cask”) and truncheon (“cudgel”). But earliest found forms of luncheon include lunshin and lunching, which are equivalent to lunch + -ing, with the suffix -ing possibly later modified to imitate a French origin. In contrast, the more common sense “light meal” is first attested for luncheon in 1652 and for lunch in 1829, so in this sense the latter is probably a shortening of the former. Lunch is possibly a derivative of lump (as hunch is from hump. See hunch for more), or represents an alteration of nuncheon, from Middle English nonechenche (“light midday meal”) (see nuncheon) and altered by northern English dialect lunch (“hunk of bread or cheese”) (1590), which perhaps is from lump or from Spanish lonja (“a slice”, literally “loin”).
1
To eat lunch.
I like to lunch in Italian restaurants.
The gentleman had left for London after lunch. Yes, alone; but he had lunched in the hotel with a lady.1909, Frank Sidgwick, Love and battles, page 291:
1 more example
Miss Otis regrets she's unable to lunch today.1934, Cole Porter, Miss Otis Regrets:
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To treat to lunch.
We dined him, we lunched him, we were photographed in his company by flashlight.1906, H. G. Wells, The Future in America: A Search After Realities: