H. P. Grice: "The heteroclitical implicatum of 'implicitum'"

  signifying a stem which alternates between more than one form when declined for grammatical case. Examples of heteroclitic noun stems in Proto-Indo-European include *wod-r/n- "water" (nominoaccusative *wódr; genitive *udnés; locative *udén) and *yékw-r/n- "liver" (nominoaccusative *yékwr, genitive *ikwnés). In Proto-Indo-European, heteroclitic stems tend to be noun stems with grammatically inanimate gender.