Profestrix

[Lavrentivs]

I have thought that the feminine of professor would be profestrix, but just read in Allen & Greenough that »[m]asculines in -sor lack the feminine« (236 a n. 2). Does that imply that it is impossible to speak of a female professor in Latin?

[adrianus]

Does that imply that it is impossible to speak of a female professor in Latin?

Minimé. De professore feminino latinè loqui potes, etiamsi masculinum verbum professoris. Similiter neutri generis est verbum verbi at de masculinis, de femininis, de neutris verbis dicere potes.

No. You can talk about a female professor in Latin, although the word "professor" will be masculine, just as the word "word" in Latin is neuter but you can talk about masculine, feminine and neuter words.

[Lavrentivs]

Πάνυ μὲν οὖν. Pro quaetione imbecilla me excusatum habe.

[Diaphanus]

I have thought that the feminine of professor would be profestrix, but just read in Allen & Greenough that »[m]asculines in -sor lack the feminine« (236 a n. 2). Does that imply that it is impossible to speak of a female professor in Latin?

Not at all.

There is a difference between the lack of an attestation of a word and the impossibility of its existence. Unfortunately, there is a general feeling that one implies the other, but attestation is not everything. Since a Rule Saying There Cannot Be Such Words has not been presented, what A&G means by "lack" is that a feminine in -trix corresponding to a masculine in -sor was not used (or at least one cannot be found).

But, actually, A&G immediately mentions expultrix and tonstrix, showing that most (not all) of the masculines lack a corresponding feminine!

So, although profestrix was not used with professor, there is no rule saying that such a word could not be created and used if you needed it.