Some categories of substantive nouns are always feminine, even when they are of the second declension, such as trees.
What other categories are there? And are there also many exocategorical examples? ...
The 2nd Declension Neuter endings are:
With a word such as auxilium (meaning help, aid), which ...
There are three neuters in the second declension ending in -us: virus, vulgus and pelagus.
(See this previous question for origin and listing of such words.)
My grammar tells me that these words are ...
Virus is a neuter word of the second declension even though it ends on -us, as evidenced by its genitive on -i (it has no plural). Are there any other such words?
Bonus question: is it possible that ...