3 Letters:
* run
* ten
* sun
* cut
* net
* urn
* use
* cur
* nut
4 Letters:
* turn
* rent
* tune
* runt
* scur
* cure
* tern
* snut
* cent
5 Letters:
* crust
* nurse
* scrun
* stern
6 Letters:
* scrunt (informal slang for "to wrinkle your nose in disgust")
Let me know if you'd like to try some more word games!