Yours, Etc.: Origins and Uses of 8 Sign-Offs
late 14c., "ecclesiastical council," from Late Latin synodus, from Greek synodos "assembly, meeting, conjunction of planets," from syn- "together" (see syn-) + hodos "a going, a way" (see cede). Used by Presbyterians for "assembly of ministers and other elders" from 1593 to c.1920, when replaced by General Council.
(from Greek synodos, "assembly"), in the Christian church, a local or provincial assembly of bishops and other church officials meeting to resolve questions of discipline or administration.