Enervated

Enervated: Although the word enervated looks like it might give you energy and nerve, it in fact does just the opposite. A person is enervated when he loses his nerve or when he is weakened.

Pristine

Pristine: People think "pristine" means “spotless” or “good as new” when it actually means “Ancient, primeval; in a state virtually unchanged from the original." 

Forest and land can be pristine.

Noisome

Yes, it obviously has to do with some unpleasant and loud noise, right?

Actually, Noisome isn't about noise. It means obnoxious or objectionable to the senses, especially the sense of smell. It's a synonym of noxious and malodorous, not cacophonous or dissonant. It's related to annoy.

Bemused

What you think "bemused" means: amused
What "bemused" actually means: confused

Poisonous

Poisonous

Poisonous—often confused with venomous—means a plant, animal, or substance capable of causing death or illness if taken into the body. Venomous means capable of injecting venom.

A rattlesnake is not itself poisonous, because if you eat one it won’t poison you. A blowfish will kill you if you eat it, so it is poisonous, but not venomous.