The origins of this form are unclear. The FEW registers the adjective tortilleux, from the 17th century, as an aphetic derivate from the Latin verb *intortillare (see FEW *intortillare). The DMLBS entry tortillus 3 gives an etymology of tortus (p.p. of torquere) followed by the suffix -illus. This citation is the only attestation of the word in medieval French.