See under circuit.
Are New Idioms Ever Created?Many idioms—expressions that are not taken literally—are so old and so familiar that we don’t think twice about using them. We say, for example, “it’s raining cats and dogs” to indicate that it’s pouring outside, and “comfortable as an old shoe” to explain an easy and familiar relationship. We can trace the etymology of some idioms to books and sayings that were first used hundreds …
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.