mid-15c., a term in logic, from Middle French predicat and directly from Medieval Latin predicatum, from Latin praedicatum "that which is said of the subject," noun use of neuter past participle of praedicare "assert, proclaim, declare publicly," from prae- "forth, before" (see pre-) + dicare "proclaim" (from PIE root *deik- "to show," also "pronounce solemnly"). Grammatical sense is from 1630s. Related: Predicative; predicator; predicatory.
1887, from Latin praedicatus, past participle of praedicare "proclaim, announce" (see predicate (n.)).
1550s, back formation from predication, or else from Latin praedicatus, past participle of praedicare "proclaim, announce" (see predicate (n.)). Related: Predicated; predicating. Phrase predicated on "founded on, based on," is American English, first recorded 1766.