English
epimer
From epi- + -mer.
Proto-Indo-European *(s)mer- ‘to fall into thinking, remember, care for’
Proto-Indo-European *(s)méros
Proto-Hellenic *(h)méros
Ancient Greek μέρος ‘part, component, region’
English polymer
English mer
Today it means
noun Any diastereoisomer that has the opposite configuration at only one of the stereogenic centres.
Language periods are conventional ranges, not dates for this word.
Etymograph / epimer