city council; municipal assembly
A local-government term for the deliberative assembly of a city. 市議会 is a closely related and often more explicit term, but 市会 is also used in official and institutional contexts.
An extraordinary session of the city council is scheduled to be convened next month.
The budget proposal for next year was passed by the city council.
彼女は市会の委員会で条例案を説明した。
She explained the ordinance proposal at a city council committee.
A new ordinance was passed by the city council.
He was elected as a city council member in the last election.
議会 is a general term for a legislative assembly at any level (national, prefectural, etc.), whereas 市会 refers specifically to a city's assembly.
city council member; city assembly member
A Sino-Japanese compound of 市, 'city,' and 会, 'meeting; assembly,' conventionally meaning the assembly of a city.