Re

Re or RE may refer to:

Geography

Re, Norway, a former municipality in Vestfold county, Norway
Re, Vestland, a village in Gloppen municipality, Vestland county, Norway
Re, Piedmont, an Italian municipality
Île de Ré, an island off the west coast of France
- Le Bois-Plage-en-Ré, a commune on that island
Re di Anfo, a torrent (seasonal stream) in Italy
Re di Gianico, Re di Niardo, Re di Sellero, and Re di Tredenus, torrents in the Val Camonica
Réunion (ISO 3166-1 code), a French overseas department and island in the Indian Ocean

Re, the second syllable of the scale in solfège
- Re, or D (musical note), the second note of the musical scale in fixed do solfège
Re: (band), a musical duo based in Canada and the United States

re (interjection), in Greek
Re (kana), the Japanese syllables written れ and レ
In re, Latin for 'in the matter of...'
- RE: and Re:, used in email subject lines

RE (complexity) (recursively enumerable), a complexity class of decision problems
- r.e., a common abbreviation for the older term Recursively enumerable
Regular expression, a sequence of characters to match text against a specified pattern
Re function in mathematics, where Re(z) denotes the real part of a complex number z

Effective reproduction number, in epidemiology
Relative effectiveness, or RE factor, an expression of an explosive's demolition power
Renewable energy
Reverse engineering
Reynolds number, a dimensionless quantity in fluid mechanics used to help predict flow patterns
Rhenium, symbol Re, a chemical element
Re, an abbreviation for "reference pressure" as Sound pressure level
Re, an abbreviation for "reference pressure" in Underwater acoustics

Realencyclopädie der classischen Altertumswissenschaft, a German encyclopedia of classical scholarship
Religious education (RE), the study of religion
Re (Egyptian religion), an ancient Egyptian god also known as Ra
Regional-Express, a type of regional train in Germany, Luxembourg and Austria
Royal Engineers, a part of the British Army
Royal Society of Painter-Printmakers, whose fellows may use the Post-nominal letters RE