The Collaborative International Dictionary of English v.0.48:
Acknow \Ac*know"\ ([a^]k*n[=o]"), v. t. [Pref. a- + know; AS.
1. To recognize. [Obs.] "You will not be acknown, sir." --B.
2. To acknowledge; to confess. [Obs.] --Chaucer.
To be acknown (often with of or on), to acknowledge; to
We say of a stubborn body that standeth still in the
denying of his fault, This man will not acknowledge
his fault, or, He will not be acknown of his fault.
--Sir T. More.