The Collaborative International Dictionary of English v.0.48:

Ecclesia \Ec*cle"si*a\, n.; pl. Ecclesi[ae]. [L., fr. Gr. ?.]
   1. (Gr. Antiq.) The public legislative assembly of the
      Athenians.
      [1913 Webster]

   2. (Eccl.) A church, either as a body or as a building.
      [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

ECCLESIA. In classical Greek this word signifies any assembly, and in this
sense it is used in Acts xix. 39. But ordinarily, in the New Testament, the
word denotes a Christian assembly, and is rendered into English by the word
church. It occurs thrice only in, the Gospels, viz. in Matt. xvi. 18, and
xviii. 17; but very frequently in the other parts of the New Testament,
beginning with Acts ii. 47. In Acts xix. 37, the word churches, in the
common English version, seems to be improperly used to denote heathen
temples. Figuratively, the word church is employed to signify the building
set apart for the Christian assemblies; but the word eclesia is not used in
the New Testament in that sense.