What does the suffix us mean?

Answer 1

The suffix "-US" comes from Latin, and denotes masculine gender, nominative case, and singular number. That is, it takes a part of a word and converts it into a masculine singular noun. For example, in the word "BONUS", "BON-" means "good", so "BONUS" is a good thing. Another example is "LOCUS". The root "LOC-" means "place", as in "location" or "allocate". So "LOCUS" literally means "The place".

The suffix "-US" is different from the suffix "-OUS", which actually takes a word and converts it into an adjective, such as "JOY" to "JOYOUS".

Some words, like "Hummus", are not counterexamples because "hummus" is not the fusion of "HUMM-" and "-US". "Humm" has no meaning on its own.

Try again. -us is not an English ending. It is Latin, and it is found on masculine, feminine and neuter nouns (e.g. carrus, manus and genus, respectively). Generally it indicates the nominative, but in some 3rd declension nouns like senatus -us, it is also the genitive, and of course neuter nominatives and accusatives are always the same.

If you meant -ous, then the second paragraph above is correct.

Answer 2

The suffix "us" in Latin-derived words typically denotes a singular masculine noun in the nominative case. For example, "alumnus" means a male graduate.