The name not withstanding Welsh Rabbit or rarebit, does not involve any bunnies. At it's most basic and delightful, it consists of cheese and some piquant seasonings, deliciously melted on toast. — a buck rarebit decadently puts a runny egg on top, sort of a Celtic Croque Madame.
Welsh rabbit first comes up in the culinary books in 1725, and the origins of the phrase are unknown, but it is believed to be a reference to the historical poverty of the Welsh. In Britain of the day, rabbit was considered the meat of the poor and the Welsh were seen as so poor that they had to settle for cheese. At some historical stage rabbit was corrupted to rarebit. And confusion, hesitation and debate over what to call this yumminess has reigned ever since. In his 1926 edition of the Dictionary of Modern English Usage, grammarian H. W. Fowler pulled no punches on his opinion: “Welsh Rabbit is amusing and right. Welsh Rarebit is stupid and wrong.” Fowler not withstanding, both rabbit and rarebit are acceptable and rarebit is more common.