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.
Hello! I'm Adam Aleksic. This year, I graduated from Harvard University with a degree in Government and Linguistics. There, I co-founded the Harvard Undergraduate Linguistics Society and wrote a thesis on Serbo-Croatian language policy, magna cum laude. In addition to etymology, I also really enjoy philosophy, trivia, vexillology, geography, board games, conlanging, art history, and law.