A new interpretation is introduced for MOND based on the Sciama's
interpretation of Mach principle and an Unruh like effect, in the context of a
generalized equivalence principle. It is argued that in a locally accelerated
frame with acceleration a the appearance of a Rindler horizon may give rise
to a constant acceleration a0β as the local properties of cosmological
horizon or Hubble length. The total gravitational acceleration inside this
frame becomes the combination of a with a0β. For aβ«a0β, the
conventional gravitational mass mgβ interacts with the dominant acceleration
as mgβa and application of Sciama's interpretation leads to the standard
Newtonian dynamics. For aβͺa0β, however, a reduced gravitational mass
mΛgβ interacts with the dominant acceleration as mΛgβa0β and the
application of Sciama's interpretation on this reduced gravitational mass leads
to MOND. This introduces a third proposal for MOND: {\it The modification of
gravitational mass}.Comment: 11 pages, throughout revisio