Source : Webster's Revised Unabridged Dictionary (1913)

Deletery \Del"e*ter*y\, a. [LL. deleterius: cf. F.
   d['e]l['e]t[`e]re.]
   Destructive; poisonous. [Obs.] ``Deletery medicines.''
   --Hudibras.

Deletery \Del"e*ter*y\, n.
   That which destroys. [Obs.]

         They [the Scriptures] are the only deletery of
         heresies.                                --Jer. Taylor.