pileus

Note: The word pilleus has been adduced as an example of the "littera-rule" in Latin (alternation between an initial syllable with long vowel followed by single consonant and the same with short vowel followed by double consonant, as in the word lītera/littera "letter"). However, the antiquity of pīleus with single l has been questioned, and the possible influence of Greek pîlos "felt" suggested. Etymologically, pilleus has been associated with both Greek pîlos and Latin pilus "hair" (see pile entry 5). A reconstructed stem *pils- has been proposed, that would tie together both Latin pilleus (from *pilsei̯os according to the Oxford Latin Dictionary) and the Greek word (allegedly from *pilsos). The *pils- hypothesis has been rejected, however, by C. Michiel Driessen ("Towards an Indo-European Term for 'felt'," Journal of Indo-European Studies, vol. 3, no. 1-2, spring-summer 2004, pp. 25-42). Driessen posits a proto-form *pis-lo- for Greek pîlos, from an Indo-European verbal base *pei̯s- "pound, crush" (see pestle entry 1), and regards Latin pilleus as of unknown origin. Other words for "felt" in Indo-European languages, which bear some phonetic similarity to pilleus and pîlos, are treated at the etymology and note at felt entry 1.