1.
main body, core, principal part
The central or primary component of something. Used to identify the main actor, agent, or entity responsible for an action or project.
学生主体のイベントだ。
It's a student-led event.
この計画の主体は地方自治体だ。
The main body behind this plan is the local government.
主体的に行動することが大切だ。
It's important to act on your own initiative.
2.
subject, agent (philosophy)
The acting self or conscious entity, as opposed to the object. Used in philosophical and academic contexts.
哲学では主体と客体の関係が問われる。
In philosophy, the relationship between subject and object is examined.
USAGE:
The adjective form 主体的 (proactive, self-directed) is very commonly used in education and business contexts, meaning to act on one's own initiative rather than passively following instructions.
The pattern ～主体 is used as a suffix meaning "-led" or "-centered" (e.g., 学生主体 = student-led).
COMMON COLLOCATIONS:
- 主体的に: proactively, on one's own initiative
- ～主体の: -led, -centered
- 実施主体: implementing body
- 主体と客体: subject and object