The English word, ecumenism is derived from the Greek word oikoumenes, which means "the inhabited world". The word is usually used with regard to movements toward religious unity. In its most broad meaning therefore, ecumenism is the religious initiative toward world-wide unity. As a minimum, ecumenism is the promotion of unity, cooperation or improved understanding between distinct religious groups or denominations within the same religion more or less broadly defined.
Two general types of ecumenism are discernible. The interfaith ecumenical movement strives for greater mutual respect, toleration and cooperation between the world's religions. Ecumenism in this sense is discussed at great length under the entry on religious pluralism. This is distinguishable from ecumenism within a faith-group.