序
ジョ, つい.で, ついで, つぐ

preface, beginning, order, precedence, occasion, chance, incidentally

JLPT1 G5 S7 F1160

As per 予# (stretch) + 广 building → rooms stretching in a line within a building → *beginning*; *order* (← beginning of a sequence) → *describe* (← describe in sequence/order; compare 敍) → *preface*.

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