I have a friend who does not like it when people say 'chag sameach' on hanukah, claiming that hanukah is not a chag.
What makes something a chag vs. not a chag?
According to most philologists/etymologists, the Biblical Hebrew word חג means something similar to a festive pilgrimage or gathering. It is thus related to the modern similar-sounding Arabic word Hajj, which refers to the Islamic obligatory pilgrimage. In that case, חג is only applicable for the three Biblical holidays when there's an obligation to make a pilgrimage to the Temple (see Deuteronomy ch. 15)
According to the Rabbinic interpretation, (see Mekhilta to Exodus 23:14 as well as the Mishnah in the beginning of Maseches Chagigah) the term 'לחוג' (to celebrate) actually refers to bringing a holiday sacrifice. Once again, there's no sacrifice to be brought on Channukah.
However, once the word became associated with holidays, I see no reason to avoid such a use, even if we've veered away from its biblical usage. After all, does anyone object to referring to a genius as a גאון?
tell your frind to go back to basics. the gemoro Shabbos 21b clearly states that chanuka is a yomtov
at the begining of the tikuney zohar chadash writes that chanuka is part of the moadim. saying chag sameach has nothing to do with the gramatical biblical conotation of the words with the root חג. woulldnt have gone down that line!
sorry for being so straight forward.