Found in the following dictionaries
TWL06 (NASPA List 2006)
"U" Definition
noun
A grade that indicates an unsatisfactory status.
Source: American Heritage Dictionary
Any of the speech sounds represented by the letter u.
Source: American Heritage Dictionary
Something shaped like the letter U.
Source: American Heritage Dictionary
The 21st in a series.
Source: American Heritage Dictionary
The 21st letter of the modern English alphabet.
Source: American Heritage Dictionary
abbreviation
Up quark.
Source: American Heritage Dictionary
Unit.
Source: Merriam-Webster
Unsymmetrical.
Source: Merriam-Webster
Upper.
Source: Merriam-Webster
Unsatisfactory.
Source: Merriam-Webster
adjective
Characteristic of the upper classes.
Source: Merriam-Webster
symbol
Uranium.
Source: Merriam-Webster
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