There are 14 13-letter words that start with 'cos'.
| cosignatories | cosmeticizing |
| cosmetologies | cosmetologist |
| cosmochemical | cosmochemists |
| cosmographers | cosmographies |
| cosmopolitans | cosmopolitism |
| cosponsorship | costermongers |
| costivenesses | cosurfactants |
Note: These 14 13-letter words that start with 'cos' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with cosm, cost, cosi, cose, cosh, coss, cosp, cosc, cosu, cosy.
4-letter words start with 'cos' (4)