Disqualify, v. t. [imp. & p. p. Disqualified; p. pr. & vb. n. Disqualifying.] — Webster enters it under “disqualify”
1. To deprive of the qualities or properties necessary for any purpose; to render unfit; to incapacitate; -- with for or from before the purpose, state, or act. My common illness disqualifies me for all conversation; I mean my deafness. Swift. Me are not disqualified by their engagements in trade from being received in high society. Southey.
2. To deprive of some power, right, or privilege, by positive restriction; to disable; to debar legally; as, a conviction of perjury disqualifies a man to be a witness.
Shades of meaning
Fernald lists disqualified only as an antonym, under adequate.
He lists it without comment; the entries above explain its neighbors.