Ecumenical is an adjective describing something as including persons of various Christian religions or churches. It can also be used for things which encourage or promote unity among the differing Christan sects. Sometime it states that something is global or applicable to all Christian churches.
The adverb form is ecumenically.
Ecumenism, or sometimes referred to as ecumenicalism, is a general movement of churches toward unity with other sects, such as the Roman and Greek Orthodox sects of Catholicism. An ecumenist is someone who believes in or practices this concept.