R2

R2, R02, R.II, R.2 or R-2 may refer to:

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R² or r² (pronounced R-squared), the coefficient of determination of a linear regression in statistics
R², the two-dimensional real coordinate space in mathematics
R2: Risk of explosion by shock, friction, fire or other sources of ignition, a risk phrase in chemistry
R2 RNA element, a cis-acting element identified in R2 retrotransposons which is involved in priming the reverse transcription process
ATC code R02 Throat preparations, a section of the Anatomical Therapeutic Chemical Classification System
Haplogroup R2 (Y-DNA), a human Y-chromosome haplogroup
receptor 2, the second in line of a series of cellular receptors, generally at the end of an acronym
Gangrene (ICD-10 code)
Robonaut 2, a NASA humanoid robotic development project
R2 signalling, a family of telephony protocols for line and register signalling

R2 (Rodalies de Catalunya), a commuter rail line in Barcelona, Catalonia, Spain
R2 (RER Vaud), an S-Bahn line in the canton of Vaud
Wilmington/Newark Line (R2 Wilmington/Newark line)
Warminster Line (R2 Warminster line)
Radial Road 2 or R-2, an arterial road of Manila, Philippines
Autopista Radial R-2, a Spanish radial motorway connecting Madrid to Guadalajara and passing through Alcobendas and connecting to N-320
R2 expressway (Slovakia)
R2 Marine Dr, an express bus route in Metro Vancouver, British Columbia, Canada
R2 road (Zimbabwe), a road connecting Plumtree and Harare
Orenburg Airlines (IATA code)

R2, a sub-class of Group R rally cars
DFW R.II, a 1918 German bomber aircraft
Fiat R.2, a 1919 Italian reconnaissance aircraft
HMS Zest (R02), a World War II British Royal Navy Z-class destroyer
Jaguar R2, Jaguar Racing's car for the 2001 Formula One season
Linke-Hofmann R.II, a World War I German bomber aircraft
ORA R2, a Chinese electric city car
Panzer 35(t), a Czech tank whose Romanian model was known as the R-2.
Polikarpov R-2, a Soviet Union copy of the 1931 British Airco DH.9A light bomber aircraft
Ross R-2 Ibis, a glider
Subaru R2, a 2003 Japanese car
USS R-2 (SS-79), a 1918 R-class coastal and harbor defense submarine of the US Navy

BBC Radio 2, a British radio station
R-2 (missile), an improved version of German V-2 rocket manufactured by the Soviet Union
R2 is a rank of United States research university in the Carnegie Classification of Institutions of Higher Education