tall order

tall order idiom
A goal that is hard to fulfill or achieve, as in Getting a thousand new subscribers is a tall order indeed. This expression uses tall in the sense of “impressively great” or “difficult.” [c. 1900]

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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