manifest. 1  readily perceived by the eye or the understanding; evident; obvious; apparent; plain: a manifest error. 2  Psychoanalysis. of or relating to conscious feelings, ideas, and impulses that contain repressed psychic material: the manifest content of a dream as opposed to the latent content that it conceals.
In medicine, an adverse effect is an undesired harmful effect resulting from a medication or other intervention such as surgery. An adverse effect may be termed a  side effect , when judged to be secondary to a main or therapeutic effect.
Adverse effect: A harmful or abnormal result. An adverse effect may be caused by administration of a medication or by exposure to a chemical and be indicated by an untoward result such as by illness or death. Last Editorial Review: 5/13/2016.