In Middle English, the word hemp was stylized hempe, hemppe, henpe, henoppe, henepe, henep, and hanep. That's from Old English hænep, which traces to Proto-Germanic hanapiz, with the same definition. It's uncertain where that comes from, but it's definitely not Indo-European. The currently reigning theory is that it could be borrowed from a Scythian word sounding something like kannapis. That same word, linguists say, later evolved into Ancient Greek kannabis, which also referred to the plant. You can see where that is going: kannabis evolved into the Latin word cannabis, which was borrowed into English as the synonym for hemp. Hemp used to be used a lot more in literature, but now both are about equal; searches in Google Trends and uses in Google NGrams are about equal.
Adam Aleksic is a sophomore studying linguistics and government at Harvard University. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.