Translation

壊滅的に減らす / 大打撃を与える / 多数を破壊する

Meaning

Decimate means to destroy, kill, or severely reduce a large part of something. It is used for populations, teams, crops, budgets, and systems. The learner trap is thinking it always means reduce by exactly ten percent.

Examples

• その病気は島の鳥の個体数に壊滅的な打撃を与えました。
  The disease decimated the island's bird population.
• 突然の予算削減で研究チームは大きな打撃を受けました。
  Sudden budget cuts decimated the research team.