Pestilent Definition

exceedingly harmful deadly or sinister; "the Florida eagles have a fierce baleful look"

as if dead (used as intensives) extremely; "she was madly in love"; "deadly dull"; "deadly earnest"; "deucedly clever

(especially of medicine) of disease or anything resembling a disease

causing or capable of causing harm; "too much sun is harmful to the skin"; "harmful effects of smoking"

injurious to physical or mental health; "noxious chemical wastes"; "noxious ideas"

exceedingly harmful working or spreading in a hidden and usually injurious way; "glaucoma is an insidious disease

likely to spread and cause an epidemic disease; "a pestilential malignancy in the air"- Jonathan Swift; "plaguey fevers"

in a disagreeable manner; "it's so plaguey cold!" likely to spread and cause an epidemic disease