(n)a unit of astronomical length based on the distance from Earth at which stellar parallax is 1 second of arc; equivalent to 3.262 light years, Syn.secpar
The Collaborative International Dictionary of English (GCIDE) v.0.53Collaborative International Dictionary (GCIDE)
n. [ From parallax second. See parallax second and annual parallax, under parallax. ] (Astron.) A unit of length used in describing astronomical distances, equal to 3.26 light years, or 3.086 x 1013 km. Abbreviated pc. The derived units of kiloparsec (kpc, 1000 parsecs) and megaparsec (mpc, one million parsecs) are often found in discussion of astronomical distances. [ PJC ]