noun
just the beginning; only the start
Only when written 序の口
Figurative use derived from the sumo division; implies that the current situation is merely the first step and more is to come. Often used in the pattern 〜はまだ序の口だ.
この程度の仕事はまだ序の口だ。
This amount of work is still just the beginning.
彼の苦労はこれが序の口だった。
His hardships were only just starting at this point.
noun
jonokuchi; lowest sumo division
The lowest of the six professional sumo divisions, where new wrestlers begin their careers.
彼は序の口で全勝した。
He won all his bouts in the jonokuchi division.
序の口から十両に昇進するまでに数年かかった。
It took several years to rise from jonokuchi to juryo.
Literally 'beginning's mouth' or 'opening of the order'. Originally a sumo term for the lowest rank, later extended figuratively to mean 'just the start'.