This is a stupid test. Since definitions are not provided, I can't tell the difference between dissent and descent, idle and idol, or even lavatory and laboratory (replaying didn't help). So I have problems at the lower levels, but the fiendish level gives me no trouble because the words are unusual and don't tend to have synonyms or near-synonyms.
Oh, and Neanderthal has two acceptable spellings. I spelled it the way they wanted it, but I wonder if they would have accepted the other version?