Poustevník – Is there a feminine form of this noun, or is it always masculine, even if the subject is feminine?
For example: Nechtěla bych žit jako poustevník? – I would not want to live like a hermit.
there is a feminine form, poustevnice.
The masculine can, however, be used as a generic term, so your sentence Nechtěla bych žít jako poustevník. is fine.
I strongly advise to avoid using this generic when closely connected to clearly female grammar forms, as in V lese žila stará poustevník, která léčila zvířata., that sounds wrong.
I agree with Mori. I would just add that even a woman could compare herself to a poustevník (i.e. male hermit). On the other hand, poustevnice is the obvious female form, even though I can't recall hearing it (I have never heard of female hermits but may have missed some history lessons . And because the female form is so obvious, it sounds fine to me even if a little unusual.
The example is not suitable. Instead of poustevník we could use any noun of any gender.
Nechtěl bych žít jako tento herec. = ... like this actor.
Nechtěla bych žít jako tento herec. = ... like this actor.
Nechtěl bych žít jako tato herečka. = ... like this actress.
Nechtěla bych žít jako tato herečka. = ... like this actress.
Nechtěl (nechtěla) bych žít jako zvíře. = ... like an animal.
In principle there is no agreement in gender.
On the other side:
She refused several suitors' offers of marriage and became a hermitess on the banks of the Severn River in Somersetshire.
Odmítla několik nabídek k sňatku a stala se poustevnicí ....
Maybe just one thought - the expression "poustevnice" sounds very unusual to me and it is kind a weird a bit - but grammaticaly it is definitely right... in the context above (posted by bibax - "Odmítla několik sňatků a stala se poustevníci"...) I would rather use a synonym... for example "sammotářka" ("samotářkou" in the proper case according to the context) ("samotář" = masculine)
Both words are different but in some cases they could be substitued (in my opinion) - especially if you want to avoid using unusual, less-frequent words like "poustevnice"
However, "samotář" is more common word and sounds less, let´s say, "educated"
Maybe I am wrong but this is how I understand it...