Is this only used when describing a male reader? i.e., would the feminine form be читателья?
You never got an answer, so... читательница
-ель > -ельница seems like a common pattern
Didn't we just learn that this is the word for "teacher"? Why is my answer wrong - especially if (by the other comments here) this is the word for a male person who reads aloud?
No, читатель is a person who reads something. A reader like an e-reader or Adobe Reader is colloquially referred to as "читалка". Formally, it is "устройство для чтения" or "программа для чтения" (a device for reading / a program for reading).
Lol, I'd just graduated from DLI and the very first Russian conversation I heard on the street was in San Francisco where two gentlemen were talking about meeting: 'на ланч' :>/
And what is a reader in English? Practically speaking there is no such thing. I suppose you could call a computer scanner a reader because it can scan text. But you would not call it a reader, you would call it a scanner. I suppose that if we were in the middle ages we might own a slave who reads to us. Again, very unusual situation. In this case you would say "The slave who reads to us", not our reader.