(1):

(n.) An expression which inveighs or rails against a person; a severe or violent censure or reproach; something uttered or written, intended to cast opprobrium, censure, or reproach on another; a harsh or reproachful accusation; - followed by against, having reference to the person or thing affected; as an invective against tyranny.

(2):

(a.) Characterized by invection; critical; denunciatory; satirical; abusive; railing.