liberal faction; reformist group
Refers to a group or faction within an organization (often political, labor, or corporate) that advocates for reform or progressive change. Often contrasted with 保守系 (conservative faction).
The liberal faction within the party proposed a new policy.
The union's reformist group is strongly demanding a wage increase.
革新 means 'reform' or 'innovation' in general, while 革新系 specifically denotes a group or faction characterized by such reformist stance.
Compound of 革新 (reform, innovation) and 系 (group, faction). The exact historical derivation is uncertain, but the term is conventionally used to label progressive or reformist factions within organizations.