INJECT definition: 1. to use a needle and syringe (= small tube) to put a liquid such as a drug into a person's body…. Learn more. To inject is to give an injection, or a shot. When your doctor tells you that you need a flu shot, she wants to inject you with a vaccine that will help keep you from getting sick. You are most likely to hear the verb inject at the doctor's office. To inject someone with a substance such as a medicine means to put it into their body using a device with a needle called a syringe. INJECT meaning: 1. to use a needle and syringe (= small tube) to put a liquid such as a drug into a person's body…. Learn more. The simple definition of INJECT is to force a liquid medicine or drug into someone or something by using a special needle—often + into —often + with. The meaning of INJECT is to introduce into something forcefully. How to use inject in a sentence. Botox® Memberships are now available. Get Botox® for $7.54/unit. Become a member today! Now serving California | Arizona | Colorado | Texas | Washington. Learn what inject means with clear definitions, pronunciation, synonyms, and real-world examples. Simple explanations to help you use inject correctly. To inject is to give an injection, or a shot. When your doctor tells you that you need a flu shot, she wants to inject you with a vaccine that will help keep you from getting sick. You are most likely to hear the verb inject at the doctor's office. Define inject. inject synonyms, inject pronunciation, inject translation, English dictionary definition of inject. tr.v. in·ject·ed , in·ject·ing , in·jects 1. To force or drive into something: inject fuel into an engine cylinder; inject air into a liquid mixture.