The story
- Proto-Indo-European*men-
- Proto-Hellenic*mónwos
- Ancient Greekμόνος (mónos)
- Ancient Greekμονο- (mono-)
- Englishmono-
- Proto-Indo-European*dʰeh₁-
- Proto-Indo-European*dʰéh₁s
- Proto-Indo-European*dʰh₁sós
- Proto-Hellenic*tʰehós
- Ancient Greekθεός (theós)
- Ancient Greekθεο- (theo-)
- Latintheo-
- Englishtheo-
- Englishtheism
- English todaymonotheism
A learned 17th-century coinage, mono- + theism, from (μονός (monós, “one”)) and (θεός (theós, “god, deity”) + -ισμός (-ismós)) The term parallels the earlier polytheism, atheism (the simplex theism being slightly later). The term was coined by Henry More, ca. 1660, in explicit juxtaposition with both atheism and polytheism. It was redefined through etymological fallacy by Daniel Webster ca. 1828.
Etymology from Wiktionary, CC BY-SA 4.0.