Grammatical term for words such as bittersweet and tragicomedy.

Bertie old bean, the last time I saw you was in court, pip pip, what ho, and all that beastly carrion.

The only answer I can conjure is oxymoronic paradoxy or oxymoraparadoxy but I did toy with logolog for quite some time.

Oh I say, you are a brick. Doubtless the old grey matter has been working overtime as has mine (well, what's left of it).

Here at home I have checked two dictionaries of literary terms as well as Roget's thesaurus and the Oxford thesaurus. Plus Fowler's Modern English Usage and all the relevant sites I can find on line. Result: zilch.

I've also tried searching for words beginning and ending with the same three letters in the same order. Although there are quite a lot listed, none meets Bill's definition and none relates to grammatical expression.

And yet, it seems that several GFQ competitors have had no trouble finding the answer. I had considered submitting "oxymoronoxy" as my answer but the word simply doesn't exist. I really am puzzled by this one.

did you look up "dvandva"????

That's one I've got right.However what did you put for No. 50 Ballyboy?

http://encyclopedia.thefreedictionary.com/bittersweet - look at the 8th entry. Found by googling 'bittersweet' 'compound word'