Strong's #1577: ekklesia (pronounced ek-klay-see'-ah)
 from a compound of 1537 and a derivative of 2564; a calling out, i.e. (concretely) a popular meeting, especially a religious congregation (Jewish synagogue, or Christian community of members on earth or saints in heaven or both):--assembly, church.
Thayer's Greek Lexicon:
 ̓́ 
 
  ekklēsia 
 
 1) a gathering of citizens called out from their homes into some public place, an assembly
 
 1a) an assembly of the people convened at the public place of the council for the purpose of deliberating
 1b) the assembly of the Israelites
 1c) any gathering or throng of men assembled by chance, tumultuously
 1d) in a Christian sense
 
 1d1) an assembly of Christians gathered for worship in a religious meeting
 1d2) a company of Christian, or of those who, hoping for eternal salvation through Jesus Christ, observe their own religious rites, hold their own religious meetings, and manage their own affairs, according to regulations prescribed for the body for order' s sake
 1d3) those who anywhere, in a city, village, constitute such a company and are united into one body
 1d4) the whole body of Christians scattered throughout the earth
 1d5) the assembly of faithful Christians already dead and received into heaven
 
  Part of Speech: noun feminine
Relation: from a compound of G1537 and a derivative of G2564
  Citing in TDNT: 3:501, 394
 
Usage:
This word is used 116 times:
Revelation 2:1: "Unto the angel of the  church of Ephesus write; These things saith"
Revelation 2:7: "Spirit saith unto the  churches; To him that overcometh will I give to eat"
Revelation 2:8: "unto the angel of the  church in Smyrna write; These things saith"
Revelation 2:11: "Spirit saith unto the  churches; He that overcometh shall not be hurt of"
Revelation 2:12: "to the angel of the  church in Pergamos write; These things"
Revelation 2:17: "Spirit saith unto the  churches; To him that overcometh will I give to eat"
Revelation 2:18: "unto the angel of the  church in Thyatira write; These things"
Revelation 2:23: "and all the  churches shall know that I am"
Revelation 2:29: "Spirit saith unto the  churches."
Revelation 3:1: "unto the angel of the  church in Sardis write; These things"
Revelation 3:6: "Spirit saith unto the  churches."
Revelation 3:7: "to the angel of the  church in Philadelphia write; These things"
Revelation 3:13: "Spirit saith unto the  churches."
Revelation 3:14: "unto the angel of the  church of the Laodiceans write; These things saith"
Revelation 3:22: "Spirit saith unto the  churches."
Revelation 22:16: "these things in the  churches. I am the root"