～宗
～しゅう · ～shuu · JLPT N1 · noun
sect
宗 = ancestor/origin: a sect is a teaching line traced back to one founder
禅宗 (zenshuu) = Zen sect: 禅 is Zen meditation and 宗 is lineage. Same pattern in 浄土宗 (Joudoshuu), the Pure Land sect. 宗教 (shuukyou) means religion.
宗 — roof 宀 + altar/show 示
宗 depicts an altar (示) under a roof (宀), picturing an ancestral shrine where offerings were made. From this concrete image it came to mean 'ancestor' and 'clan,' then extended to 'school' or 'sect' — a lineage of teaching traced back to a founding master.