[ceptimus]

I think their code word for 4 could be Mood. That would fit feeling, black, graveyard, and the well known acronym MUD (Multi User Dungeon). If that's right then none of the current clues (steam, socket, monarch) seem to fit very well to me, so I'm looking for permutations of 1 2 3.

Code word 2 could be cabbage or broccoli (yes there are cabbage and broccoli trees) and steam would be the best fit for that.

That leaves socket and monarch to assign to (land, locale, sea) and (path, travel, gum, round). I'm struggling here but the Monarch butterfly is known for its long distance migration, so I'm inclined to put it with the group containing path, travel, and round.

So my current guess would be 2 1 3, but I'm interested to see what the others think.