一いち大だい転てん機き

noun

major turning point; significant turning point

Emphasizes a big, life-changing or pivotal moment. Often used in formal or narrative contexts.

• 留りゅう学がくは彼かれの人じん生せいの一いち大だい転てん機きとなった。

  Studying abroad became a major turning point in his life.

• この新しん技ぎ術じゅつの登とう場じょうは業ぎょう界かいにとって一いち大だい転てん機きだ。

  The arrival of this new technology is a significant turning point for the industry.