WordReference Random House Unabridged Dictionary of American English © 2025
un•der•per•form
(un′dər pər fôrm′),USA pronunciation v.t., v.i.
un′der•per•for′mance, n.
- to perform less well than (another of its kind, a general average, etc.) or less well than expected:Surprisingly, the stock has underperformed the market indexes all year. Several of our best players consistently underperform.
- under- + perform