parsec
parsec (par"sek) , noun
[From parallax second. See parallax second and annual parallax, under parallax.]
(Astronomy) 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.