"one who steals books," 1880, from biblio- "book" + Greek kleptes "thief" (see kleptomania). Walsh calls it "a modern euphemism which softens the ugly word book-thief by shrouding it in the mystery of the Greek language."
word-forming element meaning "book" or sometimes "Bible," from Greek biblion "paper, scroll," also the ordinary word for "a book as a division of a larger work;" originally a diminutive of byblos "Egyptian papyrus." This is perhaps from Byblos, the Phoenician port from which Egyptian papyrus was exported to Greece (modern Jebeil, in Lebanon; for sense evolution compare parchment). Or the place name might be from the Greek word, which then would be probably of Egyptian origin. Compare Bible. Latin liber (see library) and English book also are ultimately from plant-words.
also cleptomania, 1830, formed from mania + Greek kleptes "thief, a cheater," from kleptein "to steal, act secretly," from PIE *klep- "to steal" (an extension of root *kel- (1) "to cover, conceal, save"); cognate with Latin clepere "to steal, listen secretly to," Old Prussian au-klipts "hidden," Old Church Slavonic poklopu "cover, wrapping," Gothic hlifan "to steal," hliftus "thief."
The word was much-derided in 19c. as a fancy term for old-fashioned thievery and an opportunity for the privileged to claim a psychological motive for criminal misbehavior.
There is a popular belief that some of the criminal laws under which the poor are rigorously punished are susceptible of remarkable elasticity when the peccadilloes of the rich are brought under judgment, and that there is some truth in the old adage which declares that "one man may steal a horse where another dare not look over the hedge." This unwholesome distrust is not likely to diminish if, in cases of criminal prosecutions where so-called respectable persons commit theft without sufficiently obvious motive for the act, they have their crime extenuated on the plea of kleptomania, as has recently occurred in several notable instances. ["Kleptomania," The Lancet, Nov. 16, 1861]
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Harper, D. (n.d.). Etymology of biblioklept. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/biblioklept