How to say "onslaught" in Japanese

• 攻撃こうげきJLPT N3approx.Common
  noun, suru verb, transitive verbCovers 'onslaught' in its core sense of a fierce attack or assault — violent action directed at a target, such as an enemy position. This is the word you want for that attacking sense.
  敵てきは夜よるに私達わたしたちを攻撃こうげきした。↗

  The enemy attacked us at night.
• 躍進やくしんCommon
  noun, suru verb, intransitive verbCovers 'onslaught' only in the sense of a rush or sweeping advance; it really means making rapid progress or great advances. For an onslaught that is an attack, this is not the word — use 攻撃.
  医師いし達たちは癌がんとの戦たたかいで大躍進だいやくしんを遂とげた。↗

  Doctors have made great strides in their fight against cancer.

Use 攻撃 for 'onslaught' as a fierce attack or assault, and 躍進 only for the looser sense of a rapid advance or rush, since 躍進 really means making great strides.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 攻撃こうげきattack
• 躍進やくしんmaking rapid progress
• 一斉攻撃いっせいこうげきgeneral attack