parsec

A unit of astronomical length based on the distance from Earth at which stellar parallax is one second of arc and equal to 3.258 light-years, 3.086 × 10¹³ kilometers, or 1.918 × 10¹³ miles.

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.

parallax second

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