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® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use buckle up in a sentence
It's like the anxiety you feelabout flying through the windshield of your car that makes you buckle up.
He's got to spit on his hands and buckle up his belt two holes tighter yet.The Life and Letters of Walter H. Page, Volume II | Burton J. Hendrick
Peter suited the action to his words, and moved the tongue of his buckle up two holes.Trapped by Malays | George Manville Fenn
Watch the deck crawl till sometimes the deck-plates buckle up into V-shaped ridges!The U-boat hunters | James B. Connolly
Is this job very tiring, for if it is, I doubt I may buckle up.'Greenmantle | John Buchan