There are 15 11-letter words that start with 'ost'.
| ostensively | ostensories | ostensorium |
| ostentation | osteoblasts | osteoclasts |
| osteologies | osteologist | osteopathic |
| osteoplasty | osteotomies | ostracising |
| ostracizing | ostracoderm | ostrichlike |
Note: These 15 11-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)