Webster's Revised Unabridged Dictionary · 1913

Untruss

Untruss , transitive verb

[1st pref. un- + truss.]

To loose from a truss, or as from a truss; to untie or unfasten; to let out; to undress. [Rare] — Dryden

Untruss , noun

One who untrussed persons for the purpose of flogging them; a public whipper. [Obsolete] — B. Jonson

Also: Untrusser