Pre-1960s London gayspeak (palare?) had secret words for many things - bona for good, vada for face, etc - and lots of that was backslang. I think drag, for clothes, was garb backwards.
I read of this sort of word being identified as an "semordnilap," an ugly coinage coming from spelling "palindromes" backwards. A google search turns up 395 hits but the 15 or so I checked were just about palindromes.