Ecclesiology
The word comes from the Greek ἐκ (ek) which means out and καλέω (kaleo) which means called or summoned, which combined form the Greek word ἐκκλησίᾱ (ecclesia) which is the New Testament word for the Church, denoting that the Church consists of those called out of the world. It also includes the Greek word λογία (logia) which means the study of.
Ecclesiology is the study of the Christian Church, it’s history, formation, structure, duties and future.
GotQuestions.org offers this explanation…
Ecclesiology helps us to understand the role of the church and our role in the church. It teaches us about the ordinances of the church, how church leadership is to be chosen and structured, and what the church is to be doing in regards to believers (worship and discipleship) and unbelievers (ministry and evangelism). A Biblical understanding of Ecclesiology would go a long way to correct many of the common problems in churches today. Above all, we must understand that the church is the Body of Christ and that each of us has a specific function and role within that body.