Poisonous
Toxic, Venomous
noun, な adjective, の adjective
When something has poison it is poisonous and toxic.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
ガラガラヘビって有毒なんですか？
Are rattle snakes venomous?
ダリンが道ばたに生えていた有毒キノコを間ちがって食べて、病院にはこばれてしまいました。
Darin ate a poisonous fungus growing on the side road by mistake and was sent to a hospital.
ビエトだけがコウイチのオナラが有毒ガスのような臭いがすることを知っている。
Only Viet knows that Koichi’s farts smell like toxic fumes.