Lexical Definition

‎συνωμοσία‎ synōmosía (soon-o-mos-ee'-ah) plot ^G:N-F
from a compound of ‎σύν‎ and ‎ὀμνύω‎

comspiracy.

• a swearing together, i.e. (by implication) a plot

Abbott-Smith

** συνωμοσία, -ας, ή (συνόμνυμι, to conspire), [in Sm.: Ez 22:25 * ;]
a conspiracy: Ac 23:13.†

Abbott-Smith References

Liddell-Scott-Jones

συνωμοσία-οσία

(sometimes wrongly written συνομ-), ἡ: (συνόμνυμι):— being leagued by oath, conspiracy, [Refs 5th c.BC+]; ξ. δήμου καταλύσεως for putting down the democracy, [Refs 3rd c.BC+]; οἱ ἐν τῇ ξ. [Refs 5th c.BC+]; οἱ ἐκ τῆς σ. [Refs 1st c.AD+]; ἡ ἐπί τινα, ἡ κατά τινος σ., [Refs]

__2 confederacy, ἡ πρὸς Ἀργείους γενομένη ξ. [Refs 5th c.BC+]
__II body of men leagued by oath, political union or club, [Refs 5th c.BC+]