There are 4 15-letter words that start with 'bla'.
| blamelessnesses | blameworthiness | 
| blasphemousness | blaxploitations | 
Note: These 4 15-letter words that start with 'bla' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with blac, blas, blan, blat, blam, blad, blaz, blab, blar, blaw, blae, blaf, blag, blah, blai, blau, blax.
4-letter words start with 'bla' (6)