Wiktionary
double-spaced
a. (context of text English) formatted so that there is a full blank line between each line of text; the style of formatting required by many entities inside business, academia, and publishing.
WordNet
double-spaced
adj. (of type or print) having a blank line between lines of type; "manuscripts must be double-spaced"
Usage examples of "double-spaced".
When it came back, forty-five pages double-spaced, Colleen suggested that he might consider cutting it for submission.
There he tore open the old lady's envelope and studied the message, which was typed double-spaced on ordinary notebook paper.