/het'euh roh ooh"see euhn, -ow"see euhn/ , Eccles.
n.
1. a person who believes the Father and the Son to be unlike in substance or essence; an Arian (opposed to Homoousian ).
adj.
2. of or pertaining to the Heteroousians or their doctrine.
[ 1670-80; heterooúsi ( os ) (Gk hetero- HETERO- + ousí ( a ) nature, essence + -os adj. suffix) + -AN ]