u

n. 21st letter of the alphabet

pron. (Informal) abbreviated form of the personal pronoun "you"

n. (Japanese) Usagi, "hare", Chinese zodiac sign

U is the twenty-first letter in the modern Latin alphabet. Its name in English is spelled u .
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"Ü", or "ü", is a character which represents either a letter from several extended Latin alphabets, or the letter U with umlaut or diaeresis.
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Ư is one of the 12 Vietnamese language vowels. It is pronounced as close front rounded vowel .This symbol does not exist in many fonts, and isn't included on any keyboards, so it is often written as either u+ or u*. The VIQR standard is u+.Because Vietnamese is a tonal language this letter may optionally have any one of the 5 tonal symbols above or below it.
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The acute accent ( ) is a  diacritic mark used in many modern written languages with alphabets based on the Latin and Greek scripts. The word acute is derived from the Latin acutus ("sharp"), itself a loan translation of the Greek  (oxýs).
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Backspace is the keyboard key that originally pushed the typewriter carriage one position backwards, and in modern computer displays moves the cursor one position backwards, deletes the preceding character, and shifts back the text after it by one position.In typewriters, a typist would, for example, type a lowercase letter A with acute accent (á) by typing a lowercase letter A, backspace and then the acute accent key (also known as overstrike). This is the basis for such spacing modifiers in computer character sets such as the ASCII caret (^, for the circumflex accent). Backspace composition no longer works with digital displays or typesetting systems. It has to some degree been replaced with the combining diacritical marks mechanism of Unicode, though such characters do not work well with many fonts, and precomposed characters continue to be used. Some software like TeX or Microsoft Windows use the opposite method for diacritical marks, namely positioning the accent first, and then the base letter on its position.
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The circumflex (ˆ) (often also called a "caret", from a non-diacritical sign with similar shape (^); also "hat" or "uppen") is a diacritic mark used in written Greek, French, Frisian, Esperanto,  Norwegian, Romanian, Slovak, Vietnamese, Romanized Japanese, Welsh, Portuguese, Italian, Afrikaans, Turkish and other languages. It received its English name from Latin circumflexus (bent about)—a translation of the Greek περισπωμένη (perispomeni).
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The double acute accent ( ˝ ) is a diacritic mark of the Latin script used primarily in written Hungarian. Consequently, it is also known as Hungarumlaut. The signs formed with diacritic marks count as letters of their own right in the Hungarian alphabet.
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The grave accent ( ` ) is a diacritical mark used in written Catalan, French, Greek until 1982 (polytonic orthography), Italian, Norwegian, Occitan, Portuguese, Scottish Gaelic, Vietnamese, Welsh, and other languages.The word grave is derived from the Latin gravis (heavy). In English the word is normally pronounced "grahv", IPA , not like grave meaning "serious" or a "tomb." It comes from French, where it is pronounced similarly: accent grave .
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A ring diacritic may appear above or below letters. It may be combined with some letters of the extended Latin alphabets in various contexts.
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Noun
1. a nitrogen-containing base found in RNA (but not in DNA) and derived from pyrimidine; pairs with adenine
(synonym) uracil
(hypernym) nucleotide
(substance-holonym) ribonucleic acid, RNA
2. a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons
(synonym) uranium, atomic number 92
(hypernym) metallic element, metal
(hyponym) uranium 235
(substance-holonym) uraninite, pitchblende
3. the 21st letter of the Roman alphabet
(hypernym) letter, letter of the alphabet, alphabetic character
(member-holonym) Roman alphabet, Latin alphabet

Adjective
1. (chiefly British) of or appropriate to the upper classes especially in language use
(similar) upper-class
(classification) United Kingdom, UK, Great Britain, GB, Britain, United Kingdom of Great Britain and Northern Ireland

n. u, 21st letter of the alphabet

n. u umlaut, German vocal

and, with, together with; also, too

n. u, 21st letter of the alphabet