Re: Virus (was Mesozoic Diseases)

[David Marjanovic <david.marjanovic@gmx.at>]

> There were also a few nouns in ­us that were feminine
> in gender: I think elm tree was one,
> hence the botanical binomial Ulmus americana.

All trees were feminine (because there were nymphs or dryads or something in 
them) and are treated as such in botanical nomenclature.

>     WARNING: ending in ­us isn¹t a 100% guarantee that a noun is second
> declension.  I have already included in this post an example of a Latin 
> noun
> ending ­us in the nominative and accusative singular which is a THIRD
> declension neuter (with a longer stem in the plural).

That is genus, stem gener- not just in the plural but in all cases except 
nominative singular, accusative singular, and vocative singular. Other 
examples are lepus, lepor- "hare", mus, mur- "mouse", and ius, iur- "1. 
law/right, 2. soup/juice".

There is also a whole declension class where nouns end in -us but are 
feminine. Examples: salus, salut- "hail", palus, palud- "swamp".