Suffixes are added to the end of a word to change its meaning or part of speech. In the case of "-ous," it's usually added to nouns or verbs to form adjectives.
For example:
* Courage (noun) + -ous = Courageous (adjective)
* Danger (noun) + -ous = Dangerous (adjective)
* Glory (noun) + -ous = Glorious (adjective)
* Fame (noun) + -ous = Famous (adjective)
So, while "-ous" itself isn't a part of speech, it plays a crucial role in creating adjectives that describe qualities or characteristics.