What does it mean?
Is it a building?
Is it the people inside the building?
Is the the belief system of the people inside the building?
Or, is it, perhaps
the people inside the building, working towards one purpose with a fervor: an insuppressible, unquenchable urge.
Well, the first time the word "church" is ever recorded is, you guessed it, in the Bible!
Jesus says to Peter, "on this rock I will build my ekklesia" (eck-clay-see-ah) Mat 16:18. Some goofy team of translators decided way back when that an appropriate English translation would be "church". As in, the building.
Nope! The English work "church" can be equated to the Greek word "kuriakee". If you see the German descendant of that Greek word, it's kirche. Now, you can see the English pronounciation, "church".
One. Major. Problem.
ekklesia

In fact, they are not similar at all. Kuriakee refers to the building. Ekklesia refers to the people.
Indeed, to be a church, as Christ defined it, is not to meet together in a building.
It is to be one people.
To meet together as a body.
To act as a body.
Does your right hand not bandage an ailing left hand? Does a mouth not cry out on a stubbed toe's behalf? Do your organs not survive off of one blood supply? Is there not a universal need for oxygen?
Let me decode what I'm saying:
We need to help one another. We need to cry out in prayer when others are in pain. We need to acknowledge and thank our Life Source. And, a crucial point is often overlooked: we must recognize our need for correction--for healing--for the breath of God, and we must accept such correction through God AND other parts of the ekklesia.
"For just as each of us has one body with many members, and these members do not all have the same function, so in Christ we, though many, form one body, and each member belongs to all the others." Romans 12:4-5