一いっ子し相そう伝でん

noun

passing down secrets from father to only one child; transmission of an art or craft to a single heir

A yojijukugo describing the traditional practice of handing down the deepest knowledge of an art, craft, or trade exclusively to one child (often the eldest son). Used in historical or traditional contexts.

• その流りゅう派はの秘ひ伝でんは一いっ子し相そう伝でんで守まもられてきた。

  The secrets of that school have been preserved through transmission from father to only one child.

• 一いっ子し相そう伝でんの技わざを継つぐ者ものは限かぎられている。

  Those who inherit the skills passed down through one-child transmission are limited.