Nu

Nu could mean:
 Nu, a letter in the Greek alphabet: lowercase ν, uppercase Ν
 Nu (kana), the Japanese characters ぬ and ヌ
 NU (sound project)
 Nu (mythology), the male form of the Egyptian goddess Naunet
 Nu (Chrono Trigger), a fictional species from the video game Chrono Trigger
 .nu, the Internet top-level domain for Niue
 Nu people, a Chinese ethnic group
 Nu river or Salween River
 U Nu or Mr. Nu, a former Burmese prime minister
 Nǀu language, a moribund Tuu (Khoisan) language spoken by the Nǁnǂe people in South Africa
 Nu Gundam, in the anime Mobile Suit Gundam: Char's Counterattack
 "Nu"? is a Yiddish word meaning "so?" now also absorbed into English meaning "so, what's happening?" or "so, what do you say?" 

In universities:
 Naresuan University, a public university in Phitsanulok, Thailand
 Niagara University, a Roman Catholic university in Niagara County, New York
 Northwestern University, an American research institution in Evanston, Illinois
 Northeastern University, an American research university in Boston, Massachusetts
 Norwich University, a private American military and traditional university in Northfield, Vermont
 National University (Philippines), a private, non-sectarian university in Manila, Philippines

In other abbreviations:
 Nunavut (NU), the largest and newest territory in the territories of Canada
 Nahdatul Ulama (NU), an Islamic group in Indonesia
 Nusselt number (Nu), a dimensionless heat transfer ratio
 Nucellar embryony (Nu+), a form of seed reproduction that occurs in certain plant species
 Bhutanese ngultrum (Nu.), Bhutan's official currency

In codes:
 Japan Transocean Air IATA airline designator
 Nicaragua NATO country code
 Niue ISO 3166 country code

In music:
 Nu metal, a fusion genre of Heavy Metal