The Collaborative International Dictionary of English v.0.48:

Frame of reference \Frame of reference\, n.
   1. an arbitrary set of spatial coordinates used to describe
      the position or motion of objects. The coordinates may be
      fixed or moving; as, a rotating frame of reference.
      [PJC]

   2. a set of assumptions or conditions that are used to
      discuss or understand something; as, a religious frame of
      reference.
      [PJC]

WordNet (r) 3.0 (2006):

frame of reference
    n 1: a system that uses coordinates to establish position [syn:
         coordinate system, frame of reference, reference
         system, reference frame]
    2: a system of assumptions and standards that sanction behavior
       and give it meaning [syn: frame of reference, frame]