"Master" in Japanese?

Question:

主
my friend thinks it means master, but I don't think so though I'm not too sure...my japanese isn't great (even though half my family is japanese -.-;)
I think it means master as in the adjective?
but what is the noun?
would it goshujin-sama? (also what's the kanji??>.<)
or sensei 先生
or something else???

thank you! :)

Answer:

主 could mean many things. Or it must be combined with another or more kanji. So 主 alone does not create any answer.