lather

Short definition from Wiktionary

Noun

1. 1
   The foam made by rapidly stirring soap and water.
2. 2
   Foam from profuse sweating, as of a horse.
3. 3
   A state of agitation.

Verb

1. 1
   To cover with lather.
2. 2
   To beat or whip.
3. 3
   To form lather or froth, as a horse does when profusely sweating.