What's up with the word "heim"?

Sæll everyone. I have been trying to find the word "home" in Icelandic and nothing seems to make sense. At first I thought that "heim=home" as a noun. Although here it is shown as an adverb, just like in Bín. Apart from that, "heima" seems to mean "at home". Am I missing something obvious? If "heim" is the correct answer, why doesn't it show up in Bín?