Unfit

Part of speech: verb (v.)

To make unsuitable or incompetent; to deprive of the strength, skill, or proper qualities for anything; to disable; to incapacitate; to disqualify; as, sickness unfits a man for labor; sin unfits us for the society of holy beings.

Part of speech: adjective (a.)

Not fit; unsuitable. -- Un*fit"ly, adv. -- Un*fit"ness, n.