Re*gres"sion (r?*gr?sh"?n), n. [L. regressio: cf. F. r'egression.]
The act of passing back or returning; retrogression; retrogradation.
Sir T. Browne.
Edge of regression (of a surface) Geom., the line along which a surface turns back upon itself; -- called also a cuspidal edge. -- Regression point Geom., a cusp.
© Webster 1913.