There are 7 4-letter words that start with 'on'.
| once | ones | only | onos | onto |
| onus | onyx | |||
Note: These 7 4-letter words that start with 'on' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with onc, one, ont, ono, onl, ons, ona, oni, ony, ong, onr, ond, onu, onw, onb.
3-letter words start with 'on' (3)