bacteroidal

Etymology tree
Ancient Greek βακτηρία (baktēría)
Proto-Indo-European *-yósder.
Ancient Greek -ῐος (-ĭos)?
Ancient Greek -ιον (-ion)
Ancient Greek βακτήριον (baktḗrion)bor.
New Latin bactēriumbor.
English bacterium
Ancient Greek -ο- (-o-)der.
Latin -o-
Proto-Indo-European *weyd-
Proto-Indo-European *-os
Proto-Indo-European *wéydos
Proto-Hellenic *wéidos
Ancient Greek εἶδος (eîdos)
Proto-Indo-European *-os
Proto-Indo-European *-ēs
Ancient Greek -ης (-ēs)
Ancient Greek -ειδής (-eidḗs)
Latin -oīdēslbor.
English -oid
English bacteroid
Proto-Indo-European *h₂el-der.?
Proto-Italic *-ālis
Latin -ālisbor.
Old French -albor.
▲
Latin -ālis
Old French -elbor.
▲
Latin -ālisbor.
Middle English -al
English -al
English bacteroidal
From bacteroid + -al.