The Collaborative International Dictionary of English v.0.48:

Cowslip \Cow"slip`\ (-sl[i^]p`), n. [AS. c[=u]slyppe,
   c[=u]sloppe, prob. orig., cow's droppings. Cf. Slop, n.]
   (Bot.)
   1. A common flower in England (Primula veris) having yellow
      blossoms and appearing in early spring. It is often
      cultivated in the United States.
      [1913 Webster]

   2. In the United States, the marsh marigold (Caltha
      palustris), appearing in wet places in early spring and
      often used as a pot herb. It is nearer to a buttercup than
      to a true cowslip. See Illust. of Marsh marigold.
      [1913 Webster]

   American cowslip (Bot.), a pretty flower of the West
      (Dodecatheon Meadia), belonging to the same order
      (Primulace[ae]) with the English cowslip.

   French cowslip (Bot.), bear's-ear (Primula Auricula).
      [1913 Webster]