bread [OE] In Old English bread was not the standard term for the familiar food. That was *loaf, which has since become restricted to a lump of bread. Bread was such an important part of the diet in the past that it came to stand for food in general. That is why the old translation of the Lord’s Prayer says ‘Give us this day our daily bread’. It also lies behind the word breadwinner [E19th] for the person whose income feeds the family and to be on the breadline [E20th]. The sense ‘money’, suggested by the similar use of dough [OE], was originally 1930s underworld slang in the USA. People have been writing bread and butter letters as a thank you for hospitality since the beginning of the 20th century, initially in the USA, but have known which side their bread is buttered since at least the mid 16th.