" pileus "

[Noun]  | "pi*le*us" | \ ˈpī-lē-əs \

1: a pointed or close-fitting cap worn by ancient Romans

2: the convex, concave, or flattened spore-bearing structure of some basidiomycetes that is attached superiorly to the stem and typically is expanded with gills or pores on the underside —called also cap

Origin: 1663 ;

 Borrowed from Latin pilleus, pīleus, pilleum, pīleum "felt cap," of uncertain origin;

  * 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 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:5|pile: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:1|pestle: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:1|felt:1}.;