Definition of "bread and butter" [bread and butter]

• Means of support; livelihood. (noun)
• The essential sustaining element or elements; the mainstay: "As ever, politics, vulgarity and sentimentality were the bread and butter of the Academy Awards” ( David Ansen). (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Half an hour later when he was propped up in bed with a cup of hot milk and a plate of bread and butter and the lamp within easy reach, Nurse Kettle looked down at him with her quizzical air."
• "Roz said: Shape-shifting and fairy-bride archetypes have always been my bread and butter as a folklorist."
• "The clutching 'normal' life of the valley diminished my awareness of something elemental that I took from the paleolithic silence and converted into paint: yet the canvases I sold for my bread and butter were usually full of colour and lightheartedness and were, in fact, mostly pictures of golf."