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 (M) can be estimated. The distance is derived by comparing this to its Apparent Magnitude (m).
Main Sequence Fitting
Stellar Distance Determination