From Longman Dictionary of Contemporary Englishfroth at the mouthfroth at the moutha) HBHto have saliva coming out of your mouth as small white bubbles b) informalANGRY to be extremely angry → froth
Examples from the Corpus
froth at the mouth• Access problems and the odd bolt on Lakeland mountain crags have had activists frothing at the mouth.• He died at a friend's flat in Rock Ferry after going into convulsions and frothing at the mouth.• He then started frothing at the mouth and had a fit.• With a strangled, gargling shriek, Carradine fell over, frothing at the mouth, arms waving.• Mortally wounded, frothing at the mouth, grinding his teeth in pain, he chose the floor instead.• Hoomey thought he could easily start frothing at the mouth, the way his colour had drained.• Then, last June, she keeled over frothing at the mouth while out partying with pals in a London club. 