(a.) Hurtful; noxious; destructive; pernicious; as, a deleterious plant or quality\; a deleterious example.

baleful baneful corroding corrosive corrupting corruptive counterproductive damaging deadly destroying destructive detrimental disadvantageous disserviceable distressing harmful hurtful injurious lethal malefic malevolent malign malignant mischievous noisome noxious ominous pernicious poisonous prejudicial ruining ruinous scatheful toxic unadvantageous unfavorable unprofitable unrewarding useless venenate veneniferous venenous venomous vicious virulent worthless