Definitions for "Line spacing"
The spacing between lines of text. In DTP programs this can be fixed at a specific size, or relative to the font size, or in terms of leading. Note Professional Page calculates both leading and line spacing from the baseline to the baseline of any two lines of text.
The distance between succeeding lines of text when printed on a page. In other words, the line spacing is the distance from the top of the characters on one line to the top of the characters on the next line.
Typographic term used to describe distance from letter baseline to letter baseline in blocks of text. Also called leading.