The Collaborative International Dictionary of English v.0.48:

Unfit \Un*fit"\, v. t. [1st pref. un- + fit.]
   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.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Unfit \Un*fit"\, a. [Pref. un- + fit.]
   Not fit; unsuitable. -- Un*fit"ly, adv. -- Un*fit"ness,
   n.
   [1913 Webster]