syringe; hypodermic needle; injector
Refers to the medical instrument used to inject or withdraw fluids. 注射器 is the general term; 注射針 (ちゅうしゃばり) specifically means the needle.
看護師が注射器を用意した。
The nurse prepared a syringe.
使い捨ての注射器を使ってください。
Please use a disposable syringe.
The doctor gave the patient an injection with a syringe.
The nurse stuck the syringe into the arm.
I loaded the diluted medicine into the syringe.
Blood was drawn with a syringe for the test.