- any plan or proposal that is grandiose, impractical, and usually unsolicited: You're always coming around here with your big ideas.
- purpose; intention; aim: What's the big idea of shouting at me?
Origin of big idea
An Americanism dating back to 1920–25
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018