Uncertain. Traditionally suggested to be a compound of manus (“hand”) + turbāre (“to unsettle, throw in to disorder”), or a deformed compound of manus (“hand”) + stuprāre (“to defile (the self)”), from stuprum, with influence from turbāre. In that case the vowel a would be expected to be long and nasalized, via /mans.t-/, as in mōnstrum. Some suggest the first part to be an unattested meaning of mās (“the male”) as “penis” (see de Vaan).
Watkins has traced the root to a Proto-Indo-European *mostr̥gʰ-, extended and metathesised from *mosgʰos (“marrow”), also found in Avestan 𐬨𐬀𐬯𐬙𐬆𐬭𐬆𐬔𐬀𐬥 (mastərəgan, “brains”) and Tocharian B mrestīwe (“marrow”). The semantic relationship is due to the widely attested belief that semen descends from the brain through the bones and is the same substance as brain matter and bone marrow; compare “the symbolic autofellatio of Finn mac Cumaill's gnawing his thumb to the marrow” and the obsolete meaning of marrow (“semen”).
- (Classical) IPA(key): /masˈtur.bor/, [mäs̠ˈt̪ʊrbɔr]
- (modern Italianate Ecclesiastical) IPA(key): /masˈtur.bor/, [mäsˈt̪urbor]
- to masturbate
- “masturbor”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
- MASTURBARE in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
- masturbor in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette, page 953/2
- “masturbor” on page 1,082/2 of the Oxford Latin Dictionary (1st ed., 1968–82)
- John A. Simpson and Edmund S. C. Weiner, editors (1989), “masturbate”, in The Oxford English Dictionary, 2nd edition, Oxford: Clarendon Press, →ISBN.
- Watkins, Calvert (1995) How to Kill a Dragon: Aspects of Indo-European Poetics, New York: Oxford University Press, →ISBN, page 535
- masturbo in Ramminger, Johann (accessed 16 July 2016) Neulateinische Wortliste: Ein Wörterbuch des Lateinischen von Petrarca bis 1700, pre-publication website, 2005-2016
- De Vaan, Michiel (2008), “mās, maris”, in Etymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill, →ISBN