There are 12 13-letter words that start with 'bla'.
| blabbermouths | blackguarding | 
| blackguardism | blacksmithing | 
| blamelessness | blandishments | 
| blanketflower | blasphemously | 
| blastomycoses | blastomycosis | 
| blastulations | blatherskites | 
Note: These 12 13-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)