masturbor.

Uncertain. * Traditionally suggested to be a compound of manus (“hand”) + turbāre (“to unsettle, throw into disorder”). Some suggest the first part to be varyingly an unattested meaning of mās (“the male”), or mālus (“pole”) as “penis” (see De Vaan via Adams). * Perhaps 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. * Watkins has traced the root to a Proto-Indo-European *mostr̥gʰ-, extended and metathesised from *mosgʰos (“marrow”), also found in Avestan 𐬨𐬀𐬯𐬙𐬆𐬭𐬆𐬔𐬀𐬥 (mastər^əgan, “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”). * If not, possibly cognate to Ancient Greek μαστροπός (mastropós, “pimp”), of unknown origin.