I refer to what is common to all three forms as the "third stem", rather than using either of the traditional terms ( past participle or supine stem). I have chosen the ordinal "third" to designate this stem because it is the third stem that Latin verbs have and because, unlike the other two stems, it cannot be associated reliably with a morphosyntactic property like "present" or "perfect".
- Aronoff (2004), a pag.54