Even with the hints provided so far, this fourth item is doing my head in. Can I just check that one of the words I'm looking for is exactly the word I think it should be based on the associations with the other three I've found, and that the other word I'm looking for isn't the common long version that Wiki tells me about, but a shorter word that means the same thing? I can see the first word in the grid, but the shape I'd have to trace is tortuous to say the least.