Short words:
* ion
* oil
* lip
* pin
* sip
* bit
* in
* on
* up
* it
* is
* an
* at
* op
* us
Longer words:
* lion
* piano
* paint
* basin
* polis (a city-state in ancient Greece)
Let me know if you want me to try and find more words, or if you'd like to try a different set of letters!