Spectroscopic Parallax is the determination of the distance to a star through Spectrography. Like Parallax, it offers a means to determine the distance to a star, but the word "parallax" is otherwise unrelated and misleading regarding the method, which is as follows: from a star's spectrum, its Spectral Class can be determined, and its Absolute Magnitude can be estimated. The distance is derived by comparing this to its Apparent Magnitude.
Main Sequence Fitting
Stellar Distance Determination