Old English mistel "basil, mistletoe," from Proto-Germanic *mikhstilaz "mistletoe" (source also of Old Saxon mistil, Dutch mistel, Old High German mistil, German Mistel, Swedish mistel), a word of uncertain origin. According to Watkins, it is a diminutive form, so called because it "is propagated through the droppings of the missel thrush," from Germanic suffixed form *mih-stu-, "urine," hence "mist, fine rain," from PIE root *meigh- "to urinate." Missel-bird "missel thrush" is attested from 1620s.
