bread and butter

bread and butter

1. The essential, sustaining element, as in The quality of the schools is the bread and butter of town property values. This idiom alludes to a basic food, bread spread with butter. [c. 1700]

2. Means of livelihood, as in John's job is the family's bread and butter. [First half of 1700s]

3. Ordinary, routine, as in Don't worry about it; this is just a bread and butter assignment. [Second half of 1800s]