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. 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. 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. Definition of inject verb in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. inject (third-person singular simple present injects, present participle injecting, simple past and past participle injected) (transitive) To push or pump (something, especially fluids) into a cavity or passage. The nurse injected a painkilling drug into the veins of my forearm. The meaning of INJECT is to introduce into something forcefully. How to use inject in a sentence. 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. inject meaning, definition, what is inject: to put liquid, especially a drug, into s.: 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. 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.