Froth n.
1. The bubbles caused in fluids or liquors by fermentation or agitation; spume; foam; esp., a spume of saliva caused by disease or nervous excitement.
2. Any empty, senseless show of wit or eloquence; rhetoric without thought.
It was a long speech, but all froth. --L'Estrange.
3. Light, unsubstantial matter.
Froth insect Zool., the cuckoo spit or frog hopper; -- called also froth spit, froth worm, and froth fly.
Froth spit. See Cuckoo spit, under Cuckoo.