form factor

Short definition from Wiktionary

Noun

1. 1
   The ratio of the RMS value to the absolute mean of a sinusoidal wave (especially to that of an alternating current)
2. 2
   Any of several functions that describe the unknown internal state of a particle
3. 3
   The emissivity of a material
4. 4
   A function that describes the scattering power of an atom as function of the scattering angle
5. 5
   A factor describing the stress distribution of a body
6. 6
   The geometry of an object, especially in engineering design; configuration.