Noxious, a.
Etymology: [L. noxius, fr. noxa harm; akin to nocere to harm, hurt. Cf. Nuisance, Necromancy.]
1. Hurtful; harmful; baneful; pernicious; injurious; destructive; unwholesome; insalubrious; as, noxious air, food, or climate; pernicious; corrupting to morals; as, noxious practices or examples. Too frequent an appearance in places of public resort is noxious to spiritual promotions. Swift.
2. Guilty; criminal. [R.] Those who are noxious in the eye of the law. Abp. Bramhall.
Syn. -- Noisome; hurtful; harmful; injurious; destructive; pernicious; mischievous; corrupting; baneful; unwholesome; insalubrious. See Noisome. -- Nox"ious*ly, adv. -- Nox"ious*ness, n.
Shades of meaning
Fernald has no entry of its own for noxious; he lists it under pernicious.
Where he writes about it:
Noxious (L. noceo, hurt) is a stronger word than noisome, as referring to that which is injurious or destructive. — from pernicious
Noisome now always denotes that which is extremely disagreeable or disgusting, especially to the sense of smell; as, the noisome stench proclaimed the presence of noxious gases. — from pernicious