In mathematics and technology

• Radius (graph theory), the minimum distance from a graph's node to the node that is farthest from it
• Radius of curvature
  Radius of curvature
  The distance from the center of a circle or sphere to its surface is its radius. For other curved lines or surfaces, the radius of curvature at a given point is the radius of a circle that mathematically best fits the curve at that point....
  
  , a measure of how gently a curve bends
• Bend radius
  Bend radius
  Bend radius, which is measured to the inside curvature, is the minimum radius one can bend a pipe, tube, sheet, cable or hose without kinking it, damaging it, or shortening its life. The smaller the bend radius, the greater is the material flexibility...
  
  , the minimum radius one can bend a pipe, tube, sheet, cable or hose without damage
• Radius of convergence
  Radius of convergence
  In mathematics, the radius of convergence of a power series is a quantity, either a non-negative real number or ∞, that represents a domain in which the series will converge. Within the radius of convergence, a power series converges absolutely and uniformly on compacta as well...
  
   (in calculus), the radius of the region where a complex power series converges
• Radius of gyration
  Radius of gyration
  Radius of gyration or gyradius is the name of several related measures of the size of an object, a surface, or an ensemble of points. It is calculated as the root mean square distance of the objects' parts from either its center of gravity or an axis....
  
  , the root-mean-square distance from a set of points or masses to a given center
• The radial coordinate in a
  • Polar coordinate system
    Polar coordinate system
    In mathematics, the polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a fixed point and an angle from a fixed direction....
    
     (2D)
  • Cylindrical coordinate system
    Cylindrical coordinate system
    A cylindrical coordinate system is a three-dimensional coordinate systemthat specifies point positions by the distance from a chosen reference axis, the direction from the axis relative to a chosen reference direction, and the distance from a chosen reference plane perpendicular to the axis...
    
     (3D)
  • Spherical coordinate system
    Spherical coordinate system
    In mathematics, a spherical coordinate system is a coordinate system for three-dimensional space where the position of a point is specified by three numbers: the radial distance of that point from a fixed origin, its inclination angle measured from a fixed zenith direction, and the azimuth angle of...
    
     (3D)
• The inradius or circumradius of a shape

As a name

• RADIUS
  RADIUS
  Remote Authentication Dial In User Service is a networking protocol that provides centralized Authentication, Authorization, and Accounting management for computers to connect and use a network service...
  
  , a network authentication protocol
• Radius (computer)
  Radius (computer)
  Radius was an American computer hardware firm founded in May 1986 by Burrell Smith, Andy Hertzfeld, Mike Boich, Matt Carter, Alain Rossmann and other members of the original Mac team specializing in Macintosh equipment....
  
  , a computer hardware firm
• Radius (music ensemble)
  Radius (music ensemble)
  Radius is a London music ensemble founded in 2007 by the British composer Tim Benjamin. The ensemble specialises in the performance of new music from around the world written by living composers and 20th-century masters...
  
  , a London music ensemble founded by Tim Benjamin
• Radius (band)
  Radius (band)
  Radius an alternative rock band from Los Angeles, California, has been noted as a band on the rise with their feel-good rock anthems. Radius captures a timeless sound, creating an emotional listening experience...
  
  , a band from Los Angeles, California
• Radius (comics)
  Radius (comics)
  Radius is a fictional character, a superhero in the Marvel Comics universe. He is a former member of the superhero team Alpha Flight. He first appeared in Alpha Flight: In The Beginning #-1, and first appeared as Radius in Alpha Flight vol...
  
  , a superhero in the Marvel Comics universe
• Radius (Chrono Cross), a character in Chrono Cross