There are various synonyms for the phrase "by injection". Some of these include "intravenous", which refers to the delivery of substances directly into the vein. "Subcutaneous" refers to the injection beneath the skin, while "intramuscular" refers to the delivery of a substance deep into the muscle tissue. "Intradermal" refers to the injection into the dermis or the layer of skin just below the epidermis. "Intra-articular" refers to the injection into a joint, while "intralesional" refers to the delivery of the substance directly into a lesion or a spot on the skin. Understanding the different synonyms for "by injection" helps individuals understand the specific method of delivery of medication or treatment.