There are multiple definitions:
adverse drug effect /event(English)
acute disseminated encephalomyelitis(English)
average direct effect(English)
antibody-dependent enhancement [phenomenon](English)
- an in vitro serological phenomenon--or a group of phenomena--in which viral infection of susceptible cells is modified by the addition of virus-reactive antibody
- Virology
- https://doi.org…linids/19.3.500