What does "ecumenism" mean?

Ecumenical doctrines and practices, especially as manifested in the ecumenical movement.

What is a synonym for "ecumenism"?

Common synonyms include: addition, affiliation, agglomeration, aggregation, agreement, alliance.

Pronounced //iːˈkjuː.mə.nɪzm//.

/iːˈkjuː.mə.nɪzm/ noun

noun ·Moderate ·College level

Noun

1
Ecumenical doctrines and practices, especially as manifested in the ecumenical movement.
2
(Christianity) the doctrine of the ecumenical movement that promotes cooperation and better understanding among different religious denominations: aimed at universal Christian unity wordnet
3
a movement promoting union between religions (especially between Christian churches) wordnet

"Tom doesn't know the difference between ecumenism and communism."

From ecumene + -ism.