A hypodermic needle or syringe is a medical instrument with a hollow needle, which is used to give injections. Hypodermic is also a noun. He held up a hypodermic to check the dosage. an instrument with a very thin hollow needle used for putting drugs directly into the body through the skin = syringe. used to give an injection beneath the skin
{i} hypodermic injection (injection of medication or drugs beneath the skin); hypodermic syringe (small syringe with a hollow needle used to inject medication or drugs under the skin)