ep·i·nas·ty \ˈepəˌnastē\noun (-es) Etymology: International Scientific Vocabulary epi- + -nasty; originally formed as German epinastie : a nastic movement by which a plant part is bent outward and often downward (as in the unfolding of a flower petal) < the opening of the bud is brought about by … epinasty — B.S.Meyer & D.B.Anderson >