spurge

Etymology 1

Inherited from Middle English spurge, from Old French espurge, from espurgier (“to purge”), from Latin expurgo (“I purge”); the bitter milky sap of these plants was formerly used as a purgative.

noun

1. Any plant of the genus Euphorbia, a diverse genus of over 2,000 species.
   But cockle, spurge, according to their law / Might propagate their kind, with none to awe, / You'd think; a burr had been a treasure trove. 1855, Robert Browning, Childe Roland to the Dark Tower Came, section X

Etymology 2

Uncertain.

verb

1. (intransitive) To emit foam; to froth; said of the emission of yeast from beer during fermentation.
   The body's somthing noysome: 'tis a stale one; / Good troth it spurgeth very monstrously. 1661, W. Cartwright, Siedge