There are 4 15-letter words that start with 'os'.
| oscillographies | osmoregulations |
| osteomyelitises | osteopathically |
Note: These 4 15-letter words that start with 'os' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with ost, osm, osc, oss, ose, osi, osn, osp, osa.
3-letter words start with 'os' (1)