Etymology: < ancient Greek μυθο-, combining form (in e.g. μυθολογία mythology n.) of μῦθος myth n. Compare French mytho- (formations in which are attested from the 16th cent.).Earliest in Middle English in the loanword mythology n., and subsequently in the 17th cent. in adaptations of Greek words, as mythographer n., mythologian n., mythologer n. Formations in English are found from the 18th cent., as mythologue n., mythoplasm n. N.E.D. (1908) gives the pronunciations (məi·þo, mi·þo, miþǫ·) /ˈmaɪθəʊ/ /ˈmɪθəʊ/, /mɪˈθɒ/; the third of these apparently relates to pronunciation of the prefix when used to form words in which the stress falls on the second syllable, as mythology n., etc.
This entry has been updated (OED Third Edition, June 2003; most recently modified version published online March 2019).