viperous

The cutting of great tracts of grass for hay stirred them into viperous action.

It's more viperous than any other snake of the viper bunch, an' its disposition is mean and yellow right through.

Over a thousand miles we dart our viperous hearts at innocent men.

Civil dissension is a viperous worm / That gnaws the bowels of the commonwealth.

Deaf, because insensible to the beauty of Keats's verse; and viperous, because poisonous and malignant.