I'm looking for two words:

The first is the term for someone who dies on their birthday,

and the second (which I may be making up) is the term for someone who has a large vocabulary...

Any help would be appreciated, Thanks!

vocabularian - an obscure term which can take that meaning link

If the baby dies inside or on it's way out of the mother then it is stillborn.

If you mean a person dies on the same calendar day as when he was born, then I don't know if there is a word for that.

If he happens to be at a birthday party in his favour when he kacks off, well we can call him unlucky. HA!

I don't know of any distinguishing word for the case described.

"Befuddler" will probably be used by some genealogist far in the future. And dying on one's birthday will save the estate some money at the stone carver, so it may deserve its own word.

Maybe we can coin "natamortuant" or "annicadaver" (the latter of which, though probably in use already as the name of some emo garage band, does roll off the tongue in a pleasing manner.)

"Poor bastard," while probably spoken under these circumstances more often than not, has too many other applications to be useful here.

..."Poor bastard," while probably spoken under these circumstances more often than not, has too many other applications to be useful here.

HA! True, but appropriate.

Natamortuant sounds a little too funeral homish; you know, like how they use every euphamism available to avoid saying "the dead guy"

Maybe "natamort?"

Since candles are used on both occasions, probably 'Candlearian' would work.

someone who dies on their birthday

If I needed such a term, I would use "someone who died on their birthday". (The generic singular use of they did not even give me pause to wonder.) If something more exotic, ad hoc, and nonce-like is desired, one could read some biographies of people who died on the same day they were born. Collection of a list of such people would be a necessary prerequisite.