Phrenetic

PHRENET'IC, a. [Gr. See Phrensy.] Subject to strong or violent sallies of imagination or excitement, which in some measure pervert the judgment and cause the person to act in a manner different from the more rational part of mankind; wild and erratic; partially mad. [It has been sometimes written phrentic, but is now generally written frantic.]

PHRENET'IC, n. A person who is wild and erratic in his imagination.