paranoiac /ˌpæɹəˈnɔɪæk/adjective 1noun 1forms 3 adjective1 •Pertaining to, or exhibiting, paranoia.Calm yourselves. The hysteria and opulent paranoiac fantasies that have spread over GCN’s pages in the wake of the general election constitute a reaction both shortsighted and silly. — 1980 noun1 •Somebody who has paranoia, a paranoid person. formsparanoiacs · more paranoiac · most paranoiac