Alternative forms 
From English dialectal (Kentish) feeze, feese (“to frighten, alarm, discomfit”), from Middle English fesen (“to drive away, frighten away, put to flight”), from Old English fēsan, fȳsan (“to send forth, impel, stimulate, drive away, put into flight, banish, hasten, prepare oneself”), from Proto-Germanic *funsijanan (“to predispose, make favourable, make ready”), from Proto-Indo-European *pent- (“to walk, go”). Cognate with Old Saxon fūsian (“to strive”), Old Norse fýsa (“to drive, goad, admonish”).
- (informal) To frighten or cause hesitation; to daunt, put off (usually used in the negative), to perturb, to disconcert.
- Jumping out of an airplane does not faze him, yet he is afraid to ride a roller coaster.
Usage notes 
- Citations for faze in the Oxford English Dictionary start in 1830; usage was established by 1890.
- The word phase is sometimes used incorrectly for faze; such notables as The New York Times and Mark Twain have made this error. This sometimes leads to the supposition that faze is an uneducated spelling of phase; they are distinct terms.