foment

Etymology

From Middle English fomenten, a borrowing from Old French fomenter, from Late Latin fomentare, from Latin fōmentum (“lotion”), from fovere (“heat, cherish”).

verb

1. To incite or cause troublesome acts; to encourage; to instigate.
   He was arrested for fomenting a riot; after all, it's bad enough being in a riot but starting one is much worse.
   Foreign governments have tried to foment unrest.
   Boris Johnson and senior Conservative ministers have vigorously condemned the violence in Washington, but have largely steered clear of condemning Trump for fomenting it. January 7 2021, Peter Walker, “Tories urged to suspend politicians who likened US violence to anti-Brexit protests”, in The Guardian
2. (medicine) To apply a poultice to; to bathe with a cloth or sponge.
   The maid had entered with us, and began once more to foment the bruise upon her mistress's brow. 1904, Arthur Conan Doyle, The Adventure of the Abbey Grange, Norton, published 2005, page 1178

noun

1. Fomentation.
   He came in no conciliatory mood, and the foment was kept up. 1892, Julian Ralph, On Canada's Frontier