Where does “intermillennial” come from?

intermillennial (English) comes from English inter, from Middle English enteren, from French entrer, from Middle French entrer, from Old French entrer, from Latin intrō, from Latin intra, from Latin interus — Contrastive or oppositional adjectival suffix.

intermillennial (English): Between millennia; occurring over more than one millennium

Definitions

  1. Between millennia; occurring over more than one millennium

Ancestry of “intermillennial”, step by step

intermillennial traces back through two separate lines of ancestry.

via English inter

StepLanguageWordMeaning
1EnglishinterTo bury in a grave; To confine, as in a prison
2Middle Englishenteren
3Frenchentrerto enter
4Middle Frenchentrerto enter
5Old Frenchentrerto enter
6Latinintrōto enter, go into, come in, get in, penetrate
7Latinintrawithin; inside; during; less than
8Latininterus
9Proto-Indo-Europeanh₁énterosinside, within
10Proto-Indo-European-terosContrastive or oppositional adjectival suffix

via English millennial

StepLanguageWordMeaning
1EnglishmillennialReferring to the 1,000th anniversary of an event...
2Late Latinmillenniummillennium
3Latin-enniumforming periods of years
4Latin-ennis
5Latinannusyear; time; season
6Proto-Italicatnosyear
7Proto-Indo-Europeanh₂et-no-
8Proto-Indo-Europeanh₂et-grass
Every word from Proto-Indo-European -teros