stir up; instigate
It is a serious crime to foment discord between communities.
fovere (warm, cherish, encourage) (Latin)
Foam starts to appear once you profusely foment (stir up) a soapy hot water bucket (2nd meaning). Science students can easily remember it as it sounds similar to fermentation. and stirring is an important part of fermentation process. f [oment] => moment. In dynamic kinetics, moment incite wheel to rotate.