early 15c., manifestacioun, "action of disclosing what is secret, obscure, or unseen; exhibition, demonstration," from Late Latin manifestationem (nominative manifestatio), noun of action from past-participle stem of Latin manifestare "to discover, disclose, betray" (see manifest (adj.)). Meaning "an object, action, or presence by which something is made manifest" is from 1785. The spiritualism sense of "phenomena by which the presence of a spirit or ghost is supposed to be rendered perceptible" is attested by 1853.
