What is the meaning of froth?

noun

• A mass of small bubbles formed in or on a liquid.
  • usage: "the beer had a thick head of foam"
  • synonyms: foam

verb

• Become bubbly or frothy or foaming.
  • usage: "The boiling soup was frothing"; "The river was foaming"; "Sparkling water"
  • synonyms: foam, fizz, effervesce, sparkle, form bubbles
• Make froth or foam and become bubbly.
  • usage: "The river foamed"
  • synonyms: spume, suds
• Exude or expel foam.
  • usage: "the angry man was frothing at the mouth"