Webster's Revised Unabridged Dictionary · 1913

Deletery

Deletery , adjective

[Late Latin deleterius: compare French délétère.]

Destructive; poisonous. [Obsolete]
Deletery medicines. — Hudibras

Deletery , noun

That which destroys. [Obsolete]
They [the Scriptures] are the only deletery of heresies. — Jer. Taylor