I. -logist /lədʒəst, lədʒɪst/ BrE AmE suffix [in nouns]
another form of the suffix ↑ -ologist
II. -ologist /ɒlədʒəst, ɒlədʒɪst $ ɑːl-/ AmE ( also -logist ) suffix [in nouns]
a person who studies or has knowledge of a particular kind of science:
a biologist