'parallax second' definitions:

Definition of 'parallax second'

From: GCIDE

parallax second \par"al*lax sec"ond\, n. An annual parallax of one second of an arc; -- applied to celestial objects outside the solar system. It is used to measure the distance of an astronomical object from the Earth. A star which has an annual parallax of one second of an arc is considered to be one parsec (3.26 light years) distant from the earth. See parsec in the vocabulary. [PJC]