Sharpen your spelling skills with this interactive test.
If the word is an adjective, the spelling is nearly always -ous, as in dangerous and poisonous. If the word is a noun, the spelling is nearly always -us: think of octopus and cactus.
"I would like to thank you so much for this great website. I have always been ashamed of my spelling but after a few lessons I am already better. It is filling in all the gaps. Thanks."
Student, France