1. bread spread with butter.
2. a basic means of support; source of livelihood; sustenance: The automobile industry is the bread and butter of many Detroiters.
Pronunciation: (bred'n but'ur),[key] —adj. 1. providing a livelihood or basic source of income; supplying the basic needs of life: a bread-and-butter job; the agency's bread-and-butter account. 2. of or pertaining to basic needs: housing and other bread-and-butter political issues. 3. basic or everyday; staple; routine.
4. expressing thanks for hospitality: a bread-and-butter letter.