interfacial

Etymology tree
Proto-Indo-European *h₁én
Proto-Indo-European *h₁entér
Proto-Italic *n̥ter
Latin inter
Latin inter-bor.
English inter-
Proto-Indo-European *dʰeh₁k-
Proto-Indo-European *-yéti
Proto-Indo-European *dʰh₁kyéti
Proto-Italic *θakjō
Proto-Italic *fakjō
Late Latin faciō
Proto-Italic *-jēs
Late Latin -iēs
Late Latin faciēs
Late Latin facia
Old French facebor.
Middle English face
English face
English interface
Proto-Indo-European *h₂el-der.?
Proto-Italic *-ālis
Latin -ālisder.
Old French -ialder.
Middle English -ial
English -ial
English interfacial
From interface + -ial.