Except for the Greeks, who pronounce it in the Creed every Sunday...
...γεννηθέντα οὐ ποιηθέντα, ὁμοούσιον τῷ Πατρί, δι' οὗ τὰ πάντα ἐγένετο...
...only the Church scholars would know about it.
Since you are on this subject, the addage "one iota" comes from this term. In Arian Christology, Christ was taught to be ὁμοιούσιος (homoiousios), that is to say—of the similar nature, versus of the same nature (homoousios).
“...only the Church scholars would know about it.”
As a convert to the Orthodox Church, I was certainly taught about it. In 40 years as a protestant prior, I had never heard the term used. I think the term is commonly known and understood in Orthodoxy.
So are you saying that the word, consubstanial comes from this?
Pronunciation, please?