Old French escroue (whence Medieval Latin scrofa (“nut, screwhole”)), is believed to be an adaptation of Latin scrōfa (“sow, female pig”);[1] but this development is not found in other Romance languages.[2] (For change in meaning, compare also Spanish puerca, Portuguese porca, both ‘sow; screw nut’, and is based on the fact that a boar's penis has a screw-like tip, making the sow's vulva equivalent to a screw nut by analogy).
Old Dutch *scrūva possibly derives from Proto-Germanic *skrūbō (“screw”), from *skru- (“to cut”), from Proto-Indo-European *(s)keru-, *(s)ker- (“to cut”), and is related to German Schraube (“screw”), Low German schruve, schruwe (“screw”), Dutch schroef (“screw”), West Frisian skroef (“screw”), Danish skrue (“screw”), Swedish skruv (“screw, peg”), Icelandic skrúfa (“screw”).
Compare also Occitan escrofa (“screw nut”), Calabrese scrufina (“screw nut”), which may be borrowings of the Old French word, or parallel developments.