Usage: 2 forms in 6 verses
Form Translated As     In Verse(s)
εκκλησίασον call an assembly of LXX.Num.20.8
hold an assembly LXX.Lev.8.3LXX.Deut.4.10
you hold an assembly LXX.Esth.4.16
εκκλησίασατε Assemble LXX.Deut.31.12
Hold an assembly LXX.Deut.31.28

Liddell-Scott-Jones

ἐκκλησιάζω (ekklēsiazō) to hold an assembly G:V

ἐκκλησιάζω-άζω,

future -άσω [Refs 5th c.BC+]: imperfect ἠκκλησίαζον [Refs 5th c.BC+] imperfect ἐξεκλησίαζον [Refs 5th c.BC+]: aorist ἐξεκλησίασα [Refs 5th c.BC+] —middle, ἐξεκκλησιάσατο, = {ἀγορήσατο}, 5th c.AD(?): Hesychius Legal icographuss.Hymns of see.:—hold an assembly, debate therein, [Refs 5th c.BC+]; τοιαῦτα ἐκκλησιάζωάσαντες having thus deliberated, [Refs 5th c.BC+]

__2 to be a member of the Assembly, . ἀπὸ τιμήματος οὐδενός [Refs]
__II transitive, summon to an assembly, convene, τοὺς αὑτοῦ στρατιώτας [LXX+4th c.BC+]:—passive, to be called together,[LXX]
__II.2 metaphorically, τινὰ πρὸς ἑαυτὸν . summon considerations before one's mind, [Refs 4th c.AD+]

LSJ Scripture Refs: LXX.Lev.8.3LXX.Jer.33.9*