1934 in publisher's jargon, "books that have been in publication for some time (prior to the current season) and are still in print;" see back (adj.) + list (n.1). As a verb, "to put on the back list," from 1983. Related: Backlisted.
"being behind, away from the front, in a backward direction," Middle English, from back (n.) and back (adv.); often difficult to distinguish from these when the word is used in combinations. Formerly with comparative backer (c. 1400), also backermore. To be on the back burner in the figurative sense is from 1960, from the image of a cook keeping a pot there to simmer while at work on another concoction at the front of the stove.
"catalogue consisting of names in a row or series," c. 1600, from Middle English liste "border, edging, stripe" (late 13c.), from Old French liste "border, band, row, group," also "strip of paper," or from Old Italian lista "border, strip of paper, list," both from Germanic sources (compare Old High German lista "strip, border, list," Old Norse lista "border, selvage," Old English liste "border of cloth, fringe"), from Proto-Germanic *liston, from PIE *leizd- "border, band."
The original Middle English sense is now obsolete. The sense of "enumeration" is from strips of paper used as a sort of catalogue. The native Old English form of the word lingered as list in a few specialized senses. List price is from 1871.
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<a href="https://www.etymonline.com/word/backlist">Etymology of backlist by etymonline</a>
Harper, D. (n.d.). Etymology of backlist. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/backlist