Define the term chemotherapy.

Hint: Chemotherapy: The use of chemicals for therapeutic effect is called chemotherapy. Chemotherapy, often just called chemo, is the use of medications to treat cancer.

Complete answer:
The treatment of cancer-related disease using chemical agents or drugs that is selectively toxic to the causative agent of the disease, such as a virus, bacterium, or other microorganisms.
Cancer is a disease that originates when cells in the body emerge abnormally and grow in an uncontrolled way. Cancer cells have propensity to divide rapidly; chemotherapy works by interfering with this, thereby preventing cancer from spreading — and sometimes even curing the disease by helping to clear out all the cancer cells in the body.

Additional Information:
Chemotherapy is the use of drugs (medicines) to cure cancer. These drugs are chosen according to the type and stage of cancer. These drugs get into the body and kill cancer cells specifically and help to inhibit spreading cancer cells to other body parts. Chemotherapy is not the only cancer treatment rather it is accompanied by either surgery or radiotherapy.
Based on the type of cancer and advancement chemotherapy is given either by swallowing a pill or a combination of drugs could be injected directly into the spine or muscles but generally, chemotherapy is intravenous, i.e. combination of drugs is injected directly into the veins.
But chemotherapy is not like a shot of injections rather there are various devices (like catheters, venous access devices) placed in the veins which control the rate of flow and amount of drugs.
The complex used in chemotherapy is cis diamminedichloroplatinum (II) or cis platin.

Note: The possibility to make a mistake is that the chemotherapy is done intravenously (injection is given directly into the veins) not intramuscular (injection is given in the muscle).