The Nuttall Encyclopedia
A female spirit of the watery element, naturally without, but capable of receiving, a human soul, particularly after being wedded to a man and after giving birth to a child.
Wood, James, ed. Entry for 'Undine'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/u/undine.html. Frederick Warne & Co Ltd. London. 1900.