Final answer:
The suffix "-ous" is used to form adjectives and usually conveys a quality or condition of the noun it describes, such as in 'courageous'. It is different from suffixes like '-us' in 'radius', which is not a descriptive suffix.
Step-by-step explanation:
The suffix "-ous" typically indicates that a word is an adjective. Adjectives are used to modify or describe nouns, and those ending with "-ous" often denote a quality or condition.
For example, the adjective courageous derived from "courage" conveys the quality of having courage. Words like radius do not follow this pattern as "-us" is part of the base word, not a suffix. Similar to "-ous", other suffixes in English such as -less and -ness, can alter the meaning of a word to describe an absence or state of being respectively.