How to say "buildup" in Japanese

• 増強ぞうきょうJLPT N1approx.Common
  noun, suru verb, transitive verbCovers buildup in the sense of strengthening or reinforcement: an increase in force, capability, or power. Typical context: a military buildup, or building up strength and defenses.
  語彙力ごいりょくを増強ぞうきょうしたい。↗

  I want to build up my vocabulary.
• 鬱積うっせき
  noun, suru verb, intransitive verbCovers the buildup of feelings: discontent, frustration, or anger accumulating inside a person, pent up without release. A less common word, suited to psychological rather than physical buildup.

Use 増強 for buildup meaning a strengthening or increase of force or capability, as in a military buildup; use 鬱積 for emotions such as frustration or anger accumulating inside a person, though it is less common.

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

• 増強ぞうきょうreinforcement
• 鬱積うっせきaccumulation (of discontent, frustration, etc.)