What does "vanishing" mean?

Vanishing: a. & n. from Vanish, v. Vanishing fraction (Math.), a fraction which reduces to the form Math. Dict. -- Vanishing line (Persp.), the intersection of the parallel of any original plane and picture; one of the lines converging to the vanishing point. -- Vanishing point (Persp.), the point to which all parallel lines in the same plane tend in the representation. Gwilt. -- Vanishing stress (Phon.), stress of voice upon the closing portion of a syllable. Rush.