1. a basic need or form of sustenance
that job is my bread and butter
Bread and butter are considered staple foods in the western world. The expression 'bread and butter' is commonly used as a noun in both a social and professional context and can be used in a couple of different ways. Firstly, in relation to something that is the primary source of income or sustenance for somebody or something, such as a job or industry, and secondly, in relation to people's most basic needs and concerns. The term is hyphenated to become 'bread-and-butter' when used as an adjective before a noun. 'Backbone' and 'lifeblood' have a similar meaning.