Simultaneous submission

Simultaneous submissions are what happens when "you submit a piece to more than one publication at the same time," in Duotrope's definition; what matters "is that multiple publications are considering the piece at the same time." The practice answers waiting, since publications "can take several months (or sometimes years) to respond." It is not the multiple submission, "when a publication is considering more than one (multiple) of your submissions at the same time." The etiquette is fixed: follow each market's rules, "mention in your cover letter that the piece is also under consideration by other publications," and "always (no exceptions!)" tell every market the moment a piece is accepted elsewhere.

For the short-story writer simultaneous submission is the normal pace of the game, declared in the cover letter; the book-length equivalent is the query letter round with literary agents, and both routes start from the slush pile question of who reads uninvited work.