Japeth is a form of the name Japa.
Japeth is also a form of the English and Hebrew name Japheth.
Japeth is not commonly used as a baby boy name. It is not in the top 1000 names.
† approx English pronunciation for Japeth: JH as in "joy (JH.OY)" ; EY as in "ate (EY.T)" ; P as in "pea (P.IY)" ; AH as in "mud (M.AH.D)" ; TH as in "theme (TH.IY.M)"