Why is it called Welsh Rabbit (Rarebit)?

TL;DR

Welsh rabbit is cheese on toast named 'Welsh' due to the Welsh love of toasted cheese, and 'rabbit' likely as an English ethnic slur for an inferior dish.

Key Points

• 1.The first printed recipe appeared in 1747 in Hannah Glasse's 'The Art of Cookery Made Plain and Easy.' She called it 'Welch rabbit' — simply toast, cheese, and mustard — and also included Scotch rabbit and two English rabbit variants, none containing actual rabbit.
• 2.Mustard is the defining ingredient that makes it Welsh rather than Scotch or English. A Scotch rabbit omits mustard; English rabbit soaks the toast in wine; the 1827 'Domestic Economy and Cookery' confirms mustard is what distinguishes Welsh from Scotch rabbit.
• 3.The Welsh had a documented love of toasted cheese (caws pobi) dating to at least 1526. A satirical tale in 'A Hundred Merry Tales' depicted St. Peter luring the Welsh out of heaven by shouting 'caws pobi,' suggesting their cheese obsession was well-known enough to mock.
• 4.The 'rabbit' name likely originated as an English ethnic slur implying inferiority. 'Welsh' was used derogatorily — e.g., 'Welsh comb' meant fingers through hair, 'Welsh crickets' meant lice — suggesting Welsh rabbit meant a poor man's substitute, though the existence of Scotch and English rabbit complicates this theory.
• 5.The name shifted from 'rabbit' to 'rarebit' around 1785, for unclear reasons. Theories include accent variation, a distinction from actual rabbit dishes, or the idea that 'rare bits' were end-of-meal appetizers, but none are well evidenced; the first written use of 'Welsh rabbit' dates to John Byrom's 1725 journal.
• 6.Welsh rarebit rose from pub food to haute cuisine, appearing in Auguste Escoffier's 'Le Guide Culinaire.' This placed it on menus at The Savoy and Ritz hotels; William Randolph Hearst also reportedly made it with pride as a late-night snack at Hearst Castle.
• 7.Welsh rarebit became culturally associated with causing nightmares, inspiring Winsor McCay's 1904 comic strip 'Dreams of the Rarebit Fiend.' Each strip featured a different nightmare always blamed on a late-night rarebit; McCay later adapted it into early animated cartoons, predating his work on 'Gertie the Dinosaur.'**