to force (someone) to make a decision or carry out a promise
to define clearly: he had a vague suspicion that he couldn't quite pin down
to confine to a place: the fallen tree pinned him down
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
How to use pin down in a sentence
While that cause may be safely discarded, the correct one is hard to pin down.
I did a little research and now, I mean, yikes, he's the guy that's okay with letting schools forcibly pin down autistic kids.
At one point in the Introduction, the coach opines, “history is hard to pin down.”Mike Leach Tackles Geronimo the Motivational Murderer | James A. Warren | August 17, 2014 | THE DAILY BEAST
But in the current crisis, appropriately enough, the nature of a Cossack remains hard to pin down.
She spent an hour and a half on her bracket strategy, trying to pin down what kind of girl Galavis would be interested in.Fans of ‘The Bachelor’ Embrace Brackets, Bookies, and Buy-ins in Online Betting Pools | Nina Strochlic | January 20, 2014 | THE DAILY BEAST
By running the pin down into the sand all the way, you can make it look just like a goldpiece lying on the floor of the cave.Us and the Bottleman | Edith Ballinger Price
Shake gently and pin down smoothly on a sheet, being careful to stretch and pin each scallop in place.Make Your Own Hats | Gene Allen Martin
Instead, he feinted with his club until he managed to pin down the venomous head.Into the Primitive | Robert Ames Bennet
Even that sweet green maiden-hair fern might pin down your foot so firmly that it would take a fish's sharp tooth to set you free.Lord Dolphin | Harriet A. Cheever
Cephas brought the rolling-pin down upon the paste again with fierce impetus.Pembroke | Mary E. Wilkins Freeman
Other Idioms and Phrases with pin down
Fix or establish clearly, as in The firefighters finally were able to pin down the source of the odor. [Mid-1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.