buckle up

buckle up idiom
Fasten a seat belt, as in All the children must learn to buckle up as soon as they get in a car. This term came into wide use in the second half of the 1900s, when seat belts became mandatory automobile equipment. Earlier they had been used mainly in airplanes.

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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