1. Noun endings:
* Masculine singular: This is the most common use. It indicates a masculine noun in the singular form.
* Examples: "virus", "campus", "octopus"
* Plural: Sometimes "-us" is used to form the plural of Latin nouns, though it's less common than "-i".
* Examples: "fungus" -> "fungi", "cactus" -> "cacti"
2. Adjective endings:
* Adjectives: "-us" can be part of Latin adjectives, particularly when they describe a masculine noun.
* Example: "bonus" (good, masculine singular)
3. Other uses:
* Medical terms: "-us" can be used in medical terms to indicate a specific condition or thing.
* Example: "thrombus" (a blood clot)
Important Note: "-us" can be a bit tricky, as its meaning often depends on the word itself and its origin. For example, the word "octopus" is Greek, not Latin, even though it ends in "-us".
If you encounter a word ending in "-us", consider its context to figure out the specific meaning of the suffix.