Greek:
Moustache:
«Μουστάκι» [muˈs̠t̠aci] (neut.) < Byzantine Greek neuter diminutive
«Μυστάκι(ο)ν» /myˈstaki(o)n/ < Classical 3rd declension masc. noun
«μύσταξ» /ˈmystɐk͡s/ (nom. sing.),
«μύστακος» /ˈmystɐkos/ (gen. sing.) -->
moustache, upper lip which is the 3rd declension fem. noun
«μάσταξ» /ˈmɐstɐk͡s/ (nom. sing.),
«μάστακος» /ˈmɐstɐkos/ (gen. sing.) -->
mouth, mouthful, morsel (of unknown etymology, possibly a substrate word), contaminated with the 3rd declension masc. noun
«βύσταξ» /ˈbystɐk͡s/ (nom. sing.),
«βύστακος» /ˈbystɐkos/ (gen. sing.) -->
moustache, also,
chin, beard (a Pre-Greek word).
Beard: (1)
«Μούσι» [ˈmus̠i] (neut.) < Fr. mouche (narrow beard descending from lower lip); (2)
«γένι» [ˈʝe̞ni] (neut.) often in plural
«γένια» [ˈʝe̞ɲa] (neut.) < Byz.Gr. neuter noun
«γένιν» /ˈgenin/ < Koine neuter noun
«γένειον» /ˈgeneːon/ a simpler variant of the Classical 3rd declension feminine noun
«γένυς» /ˈgenys/ (nom. sing.),
«γένυος» /ˈgenyos/ (gen. sing.) -->
chin, beard, edge of an axe (PIE
*ǵenus- chin).
(1) & (2) are used equally and interchangeably.
Goatee:
«Υπογένειο» [ipo̞ˈʝe̞ni.o̞] (neut.) < Byzantine Gr. neuter noun
«ὑπογένειον» /ypoˈgenion/ -->
under-beard, sub-beard, a compound: prefix & preposition
«ὑπό» /yˈpo/ < Classical preposition
«ὑπό» /hyˈpo/ + Koine neuter noun «γένειον» /ˈgeneːon/ (see earlier).