We were requested by General Assembly to supply a definition of a Missional Church.
Here is the definition we’ve proposed:

What is a Missional Church?

A Missional Church is a sent Church,
which understands its primary work
as witnessing to Christ and serving God in the world.

A Missional Church is shaped by God
for the community into which God has placed it.

A Missional Church is focused on those who don’t yet know Jesus.

A Missional Church, empowered by the Holy Spirit,
is focused on working with God in bringing fullness of life
(involving justice, healing, wholeness and reconciliation)
to all the people of the world.