How to say "injection" in Japanese

• 注射ちゅうしゃJLPT N4approx.Common
  noun, suru verb, transitive verbA medical injection given with a syringe — a shot or jab at the clinic or hospital. This is the word you want for getting an injection from a doctor or nurse.
  流感りゅうかんの予防よぼうワクチンの注射ちゅうしゃをした。↗

  I was vaccinated against the flu.
• 注入ちゅうにゅうCommon
  noun, suru verb, transitive verbThe act of injecting or pouring something into something else — an injection of a substance, not a medical shot. Use it when something is being put or poured in rather than given as a jab.
  この緊急きんきゅうな事態じたいにおいて、人事じんじや制度せいどを改革かいかくし、清新せいしんな雰囲気ふんいきと新あたらしい観念かんねんを、われわれの組織そしきの中なかに注入ちゅうにゅうする以外いがいに方策ほうさくはない。↗

  We have no other alternative but to swap horses midstream and inject a fresh atmosphere and new ideas into our organization.
• 投入とうにゅうJLPT N1approx.Common
  noun, suru verb, transitive verbPutting in or committing resources — an injection or infusion of funds, personnel, and the like. This is the figurative 'injection' of funds or resources, not a medical shot or a poured liquid.
  敵てきは新しん兵力へいりょくを投入とうにゅうした。↗

  The enemy flung fresh troops into the battle.

Use 注射 for a medical injection or shot, 注入 for injecting or pouring a liquid or substance into something, and 投入 for figuratively injecting resources such as funds or personnel.

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

• 注射ちゅうしゃinjection
• 注入ちゅうにゅうpouring
• インジェクションinjection
• 単射たんしゃinjection
• 注射液ちゅうしゃえきinjection (liquid)
• 注射剤ちゅうしゃざいinjection (drug)
• 注射薬ちゅうしゃやくinjectable drug
• 射出しゃしゅつshooting
• 投入とうにゅうinvestment