There are 4 13-letter words that start with 'ost'.
| osteomalacias | osteomyelitis |
| osteoplasties | osteosarcomas |
Note: These 4 13-letter words that start with 'ost' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with oste, ostr, osti, osto, ostl, ostm.
5-letter words start with 'ost' (1)