Disallow, v. t. [imp. & p. p. Disallowed; p. pr. & vb. n. Disallowing.]
Etymology: [Pref. dis- + allow: cf. OF. desalouer, desloer, to blame, dissuade.]
To refuse to allow; to deny the force or validity of; to disown and reject; as, the judge disallowed the executor's charge. To whom coming, as unto a living stone, disallowed indeed of men, but chosen of God. 1 Pet. ii. 4. That the edicts of Cæsar we may at all times disallow, but the statutes of God for no reason we may reject. Milton.
Note: This verb was sometimes followed by of; as, "What follows, if we disallow of this" Shak. See Allow.
Syn. -- To disapprove; prohibit; censure; reject.
Shades of meaning
Fernald has no entry of its own for disallow; he lists it under prohibit.
Where he writes about it:
Debar is said of persons, disallow of acts; one is debarred from anything when shut off, as by some irresistible authority or necessity; one is prohibited from an act in express terms; he may be debarred by silent necessity. — from prohibit
An act is disallowed by the authority that might have allowed it; the word is especially applied to acts which are done before they are pronounced upon; thus, a government may disallow the act of its commander in the field or its admiral on the high seas. — from prohibit