Webster's Revised Unabridged Dictionary · 1913

Unbolt

Unbolt , transitive verb

[1st pref. un- + bolt.]

To remove a bolt from; to unfasten; to unbar; to open.
He shall unbolt the gates. — Shakespeare

Unbolt , intransitive verb

To explain or unfold a matter; to make a revelation. [Obsolete]
I will unbolt to you. — Shakespeare