froth up

froth up (third-person singular simple present froths up, present participle frothing up, simple past and past participle frothed up)

1. (intransitive) To become frothy; to rise with a frothy surface or covered with something resembling froth.
   • 1820, John Keats, “Isabella; or, The Pot of Basil. A Story from Boccaccio.”, in Lamia, Isabella, the Eve of St. Agnes, and Other Poems, London: Printed [by Thomas Davison] for Taylor and Hessey, […], OCLC 927360557, stanza XLI, page 69:

     The Spirit mourn'd "Adieu!"—dissolv’d, and left / The atom darkness in a slow turmoil; / As when of healthful midnight sleep bereft, / Thinking on rugged hours and fruitless toil, / We put our eyes into a pillowy cleft, / And see the spangly gloom froth up and boil: / It made sad Isabella’s eyelids ache, / And in the dawn she started up awake; [...]

   • 1902, Rudyard Kipling, “How the Whale Got His Throat” in Just So Stories,

     ‘Then fetch me some,’ said the Whale, and he made the sea froth up with his tail.

   • 1911, D. H. Lawrence, chapter 8, in The White Peacock‎:

     As I passed along the edge of the meadow the cow-parsnip was as tall as I, frothing up to the top of the hedge, putting the faded hawthorn to a wan blush.

   • 1941, Emily Carr, chapter 20, in Klee Wyck‎:

     It was “soperlallie”, or soap berry. It grows in the woods; when you beat the berry it froths up and has a queer bitter taste.

• foam up