see below par.
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 under par in a sentence
If it can be purchased for less, exchange is under par and is against London.The Wonder Book of Knowledge | Various
Time is always quoted under par at a summer resort; why should the idlers heedlessly load up with too much of the stock?A Midsummer Drive Through The Pyrenees | Edwin Asa Dix
All government securities were under par, even for depreciated bank notes.Thirty Years' View (Vol. I of 2) | Thomas Hart Benton
Their bonds were sold under par, though the discount was usually hid by a trick: pay was often received in depreciated paper.Thirty Years' View (Vol. II of 2) | Thomas Hart Benton
He says if these people could count their should-have-hads they'd all be playing under par.The Wrong Twin | Harry Leon Wilson