Purl

n.
  1. A circle made by the notion of a fluid; an eddy; a ripple.
  2. A gentle murmur, as that produced by the running of a liquid among obstructions; as, the purl of a brook.
  3. Malt liquor, medicated or spiced; formerly, ale or beer in which wormwood or other bitter herbs had been infused, and which was regarded as tonic; at present, hot beer mixed with gin, sugar, and spices.
  4. (Zoöl.) A tern.