Adherent: A follower of a particular religion, church or philosophy. This is the broadest possible category of such followers and includes professing and affiliated adults and also their children (practicing and non-practicing) who may reside in a given area or country.  

Adoption (of an unreached people): Making a commitment to an unreached people until there is an indigenous, reproducing church established among them. Aspects may include prayer, research, and networking toward church planting. Sometimes called “people group adoption” or adopt-a-people.  

Advocate: People group advocates are individuals who have committed themselves to one specific people group (ethnic group), to learn about them, their environment, culture, demographics, status, etc. They pray about how churches can be established among them. They may network and partner with others to encourage their involvement.  

Affinity Bloc: Families of peoples related in aspects such as religion, culture, history, politics, and geography. In nearly every bloc there are widely dissimilar and unrelated linguistic minorities, but often there is one particular culture that is dominant. 

Church planting: Missionary role of evangelism, discipleship and training of leaders for the establishment of a body of believers, or a church. Does not refer to a physical building.  

Closed Country: Countries that limit or prevent Christian ministry by expatriates as missionaries. Alternatively they are called creative-access countries, restricted access countries, closing countries, restrictive countries, sensitive countries.  

Cluster: Grouping of peoples within each affinity bloc which are closely related peoples and, for strategic purposes, may be clustered together. These relationships are often based on a common identity of language and name, but sometimes on the basis of culture, religion, economy, or dominance of one group over another.  

Collaboration: To combine forces and resources to meet a common goal.  

Contextualization: Adapting a biblical concept, mission method, etc., without changing the substance, to make it understood within the context of an ethnic culture. 

Ethnocentrism: Seeing the world through self-colored glasses, so that your culture always looks best and becomes the pattern everyone else should fit into. By no means is ethnocentrism restricted to the majority culture in a country, but it is a nearly universal tendency among humans. 

Ethnolinguistic People: An ethnic or racial group speaking its own language. A people group distinguished by its self-identity with traditions of common descent, history, customs and language. Also known as a people.  

Evangelism: An effective presentation of the Gospel by someone from the same culture, and within a culture where the missiological breakthrough of a viable church has already taken place.  

Expatriate: One who has taken up residence in a foreign country.  

Field: The location where ministry, church planting, and evangelism takes place.  

Field-based: Strategy determined by those on the field, rather than from those at the “home,” sending, or resource base.  

Frontier: Pertaining to unreached areas or peoples.  

Frontier Missions: Cross-cultural evangelism to People Groups where no missiological breakthroughs have occurred (or among a People Group where no viable church exists).  

Harvest Field: All who are not true Christians; not part of the Body of Christ.  

Harvest Force: Those of the Body of Christ who are involved in a direct or indirect way in helping to bring in the harvest of souls.  

Indigenous peoples or persons: Those individuals or groups who originate from a particular area; a national, a native.  

Joshua Project Unreached Peoples List: A listing of “country-distinct” peoples each over 10,000 in population that were chosen by their ethnolinguistic distinction and their status of being less than 2% Evangelical and less that 5% Christian adherents.  (see Joshua Project)

Martyr: A Christian believer who dies in a situation of witness as a result of human hostility.  

Mission: The loving work of God to bring humankind to himself as the Church (missio dei). Secondarily, the overall ministry of the Church for world evangelization. 

Missiology: The study of missions and mission strategies; the theology of missions; how and why we do missions. 

Mission agency: A Christian organization helping to further God’s work in the world. “Mission board” and “sending agency” are virtually the same thing. 

Missionary: One who is sent with a message. The Christian missionary is one commissioned by a local church to evangelize, plant churches and disciple people away from his home area, among people of a different race, culture or language (i.e. cross culture).  

Missions Resource Organization: These agencies support the work of field missions and missionaries by offering information, resources, materials, and mobilization of the Church.  

National: Any person who is from the country to which a missionary is going.  

Network: An extended group of people with similar interests or concerns who interact and remain in informal contact for mutual assistance or support.  

Non-Resident Missionary: Professional career missionary who is working towards the evangelization of a particular people or cluster, but resides outside the group, usually in a city with good international communications facilities and no surveillance. 

Para-church: Refers to a Christian organization independent of any church denominational structures. 

Partnership: An association of two or more autonomous bodies who have formed a trusting relationship and agreed upon expectations by sharing complementary strengths and resources, to reach their mutual goal.  

People Group: A significantly large sociological grouping of individuals who perceive themselves to have a common affinity with one another. From the viewpoint of evangelization, this is the largest possible group within which the gospel can be spread without encountering barriers of understanding or acceptance.  

Prayer journey: A trip to pray on location for the lost. Team members may spend extended time prayerwalking, asking God to bring the Gospel to that unreached people group. It does not entail evangelism or mercy ministries.  

Prayerwalking: Praying “on-site with insight.” Taking prayers outside the church walls as we walk through an area. Praying in the very places we expect to see God bring forth His answers. Usually low profile and unobtrusive in appearance. 

Praying Through the Window: Prayer initiatives developed for the purpose of worldwide focused prayer for the countries and peoples in the 10/40 Window.  (see Pray Thru the Window) 

Reached/unreached: A term that is widely used today to describe people groups and areas that have or have not responded to the preaching of the gospel. Strictly, it should be a measure of the exposure of a people group to the gospel and not a measure of the response.  

Regular Missions: Pertaining to cross cultureal evangelism by a different-culture worker, in association with same-cultural workers if possible, where a missiological breakthrough has already taken place.  

Strategy Coordinator: One who develops and implements a strategy to reach a people group, working with a team or network. Support: The finances and prayer needed and given for mission trips & work. 

Syncretism: Fusion of differing systems of belief. Mixing Christianity with heresy.

Synergy: The interaction of two or more agents or forces so that their combined effect is greater than the sum of their individual effects. Cooperative interaction among groups that creates an enhanced combined effect.  

Tentmaker: A cross-cultural witness who works at a paying, usually secular, job overseas. Often they are able to gain entry into “closed” countries which restrict traditional mission efforts.  

10/40 Window: The area of the world between latitudes 10 degrees and 40 degrees north of the equator in the Eastern hemisphere, covering North Africa, Middle East and Asia. The window has in view most of the world’s areas of greatest physical and spiritual need, most of the world’s least-reached peoples and most of the governments that oppose Christianity. (see 10/40 Window.org and Window International Network) 

Unreached /Least Reached People Group:  A people or people group among whom there is no viable indigenous community of believing Christians (i.e.  no church) with adequate numbers and resources to evangelize their own people without outside (cross-cultural) assistance.  The general defining critieria is a People Group that is less than 2% Evangelical Christian and less than 5% Christian Adherents.  (see Joshua Project) 

World Evangelization: The whole Church taking the whole gospel to the whole world. The goal of giving every person the opportunity to hear the gospel in a way they understand, to become disciples of Christ, and to join with others in fellowship without leaving their own culture or people.