(adj.) Of the same size, extent, or duration as another; proportionate.
L.L. commensuratus, from → com- "together, with" + mensuratus, p.p. of mensurare "to measure," from menusra "measure."
Hammasâ, from ham- "together," → com- + masâ "size, greatness," from Mid.Pers. masây, masâk "size," Av. masah- "size, greatness, length," maz-, masan-, mazant- "great, important," mazan- "greatness, majesty," mazišta- "greatest," cf. Skt. mah-, mahant-, Gk. megas, L. magnus; PIE *meg- "great."
Fr.: orbites commensurables
Of two bodies orbiting around a common barycenter, when the orbital period of one is an exact fraction, for example one-half or two-thirds, of the other.