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.
unfit in French is invalide, inapte
unfit in German is ungeeignet, untauglich
unfit in Italian is inadatto, inabile al lavoro, disadatto
unfit in Latin is indignus
unfit in Spanish is incapaz, echadizo