I don't know what "viri defessus" means. Here's why --

"defessus" is the masculine, singular, nominative form of the adjective meaning "weakened."

In here (http://econrad.net/latin/), go into the first and second declension sections. The whole adjective is usually listed as "defessus, defessa, defessum" -- in order of masculine, feminine, and neuter forms.

"viri" however, is a noun that is NOT in the masc, s, non form. Go here (http://econrad.net/latin/ln2.html) and scroll down to the declension of the word "vesper" which forms its ending exactly as the word "vir" does.

In order to have "defessus" modify "vir," here's what you would need to use, depending on the use in the sentence (subject, object, or whatever):

SINGULAR:
vir defessus
viri defessi
viro defesso
virum defessum
viro defesso


PLURAL:
viri defessi
virorum defessorum
viris defessis
viros defessos
viris defessis


In other words, the adjective's ending must match the case, gender, and number of the noun it modifies.

So then when do I add the US to the end of the sentence?

Wait, I add the us for singular only correct? Masculine plural would be like viri defessi or

is this correct?

Pueri sunt amici quae in Romani habitant.

(The boys are friends who live in Rome)

For some reasons its the masculines that throw me off. Like I understand the ae and nt for feminine, but for masculine, im a bit confused of the whole ordeal.

-nt is a verb form ... it's for when the subject is 3rd person plural. -ae is an ending that is used on feminine nouns and adjectives.

-------------------
This is correct, yes:

Pueri sunt amici quae in Romani habitant.

(The boys are friends who live in Rome)

And yes ... this is correct, too:

Wait, I add the us for singular only correct? Masculine plural would be like viri defessi

Correction:

... amici quae ...

should be ... amici qui ...

I haven't learned the qui yet! But thanks so much!:) So only add the us if im making it a masculine singular sentence?

Yes, you'd add -us if it's masculine singular nominative (the subject or the predicate noun or adj).

Each case has its uses, and they don't overlap.

It takes LOTS of memorizing to get it all straight, and you need to be constantly matching adjectives to their nouns and subjects to their verbs!! I don't know how the Romans did it!!

Thanks for helping me!

You're welcome!

I notice that the links I put in the first post of this thread don't launch correctly because of the closing parentheses marks. I'll have to remember to put a space there if I do that again. Here are the links that actually work!

http://econrad.net/latin/

http://econrad.net/latin/ln2.html