A time permissible for cocktails or some other alcoholic drink. Yardarm means either end of the outer portions of a square sail, and presumably this term alludes to the cocktail hour on a pleasure yacht, after the sun has begun to sink. It is used more in Britain than in America, where in fact it is dying out. Rudyard Kipling had it in From Sea to Sea (1899): “The American does not drink at meals as a sensible man should. Also, he has no decent notions about the sun being over the yardarm or below the horizon.”