Definition of homoousian in US English:

homoousian

(also homousian)

noun

historical
  • In the fourth-century Arian controversy, a person who held that God the Father and God the Son are of the same substance.

    Compare with homoiousian
    • ‘The arguments between homoiousians and homoousians would be hysterically ridiculous if it weren't for the amount of blood shed over the letter ‘i’.’

Origin

Mid 16th century: from ecclesiastical Latin homousianus, from homousius, from Greek homoousios, from homos ‘same’ + ousia ‘essence, substance’.

Pronunciation

homoousian

/ˌhōmōˈo͞osēən/