noun, often capitalized, often attributive
\ ˈyü How to pronounce u (audio) \
plural u's or us\ ˈyüz How to pronounce us (audio) \

Definition of u

 (Entry 1 of 5)

1a : the 21st letter of the English alphabet
b : a graphic representation of this letter
c : a speech counterpart of orthographic u
2 : a graphic device for reproducing the letter u
3 : one designated u especially as the 21st in order or class
4 [abbr. for unsatisfactory]
a : a grade rating a student's work as unsatisfactory
b : one graded or rated with a U
5 : something shaped like the letter U


abbreviation (1)

Definition of u (Entry 2 of 5)

1 unit
2 unsymmetrical
3 physics up (see up entry 4 sense 5)
4 upper
\ ˈyü How to pronounce U (audio) \

Definition of U (Entry 3 of 5)

: characteristic of the upper classes


abbreviation (2)

Definition of U (Entry 4 of 5)

1 unsatisfactory
2 uracil

Definition of U (Entry 5 of 5)


Examples of u in a Sentence

Noun There are three u's in “unusual.” a word that starts with u

First Known Use of u


before the 12th century, in the meaning defined at sense 1a


1954, in the meaning defined above

History and Etymology for u


upper class

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Time Traveler for u

Time Traveler

The first known use of u was before the 12th century

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Statistics for u

Cite this Entry

“U.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/u's. Accessed 6 December 2019.

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More Definitions for u

How to pronounce U (audio)

English Language Learners Definition of u

: the 21st letter of the English alphabet
British : a grade given to a student whose work is judged as not satisfactory


noun, often capitalized
\ ˈyü \
plural u's or us\ ˈyüz \

Kids Definition of u

1 : the 21st letter of the English alphabet
2 : a grade rating a student's work as unsatisfactory

Medical Definition of U

 (Entry 1 of 2)


Medical Definition of U (Entry 2 of 2)


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More from Merriam-Webster on u

Rhyming Dictionary: Words that rhyme with u

Spanish Central: Translation of u

Nglish: Translation of u for Spanish Speakers

Comments on u

What made you want to look up u? Please tell us where you read or heard it (including the quote, if possible).


very cautious or careful

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