HALLUCINATE is a 11 letter word that starts with H.
\Hal*lu"ci*nate\, v. i. [L. hallucinatus, alucinatus, p. p. of hallucinari, alucinari, to wander in mind, talk idly, dream.] To wander; to go astray; to err; to blunder; -- used of mental processes. [R.] --Byron.