[New Latin mysticētus, from Greek mustikētos, textual transmission error (found in early modern editions of Aristotle's Historia animalium) of the phrase (ho) mūs to kētos, (the) whale (called) the mouse (Aristotle's designation for an unknown kind of aquatic animal) : mūs, mouse; see mūs- in the Appendix of Indo-European roots + to : neuter nominative and accusative singular definite article ; see to- in the Appendix of Indo-European roots + kētos, sea monster, whale (of unknown origin).]