My kid came home from school one day insisting that the thing we light on Chanuka is not a m'nora but a chanukiya. I replied that that's the word most Israelis use now but that m'nora is a perfectly good word for it anyway. I then took out an Aruch Hashulchan to point out the word m'nora — but didn't find it. (He seems to use neros exclusively. I might have missed it, though: I didn't look very thoroughly.) So my question is this: am I right? I mean, I know I'm right that m'nora has long been used to mean a Chanuka-thing, but (1) what's the earliest it's attested in print and (2) what's the earliest chanukiya is attested in print? (And any other information about the prevalence of the two words.)
Don't know the earliest attestation of menorah for what we light on Chanukah, but it is mentioned parenthetically in Shulchan Aruch, Orach Chaim 671:7 (and from there in Aruch Hashulchan 671:25), where it's talking about how to set up the menorah in shul. All of the rest of their references to the Chanukah lights indeed use the term נר(ות) חנוכה. I'd guess that indeed the average person in those days didn't have a specially-designed candelabra for this purpose (or if they did, it wasn't branched like the original menorah), whereas the community as a whole might have one for use in shul, hence the terminology.
As for chanukiyah, Hebrew Wikipedia says that this term was coined by Eliezer Ben-Yehuda's wife Hemda in the late 19th century.
Sedei Haaretz Volume 3 - Orach Chaim Siman 38 was published in the year 5544 = 1784. This was written by Rabbi Avraham Bar Shmuel Meyuchos Zatzal who was a Rabbi in Jerusalem in his times. In Siman 38 he has a question from Rabbi Eliezer Nachum Zatzal who was the author of Chazon Nachum. In the question he asks regarding something which is called a Chanukia
ראובן היה לו פמוט של־נחושת, שקורין אותו חנוקיאה
You see from here that the word Chanukia was in use in 1784, and there was no issue with calling a Menora a Chanukia.
Thanks to http://www.maharitz.co.il/?CategoryID=272&ArticleID=518&dbsAuthToken= for this answer.