(HMO) - Health maintenance organization. When you sign up for an HMO, you choose one doctor to coordinate all your health care. This doctor, your "primary care physician," learns your entire medical history. He or she recommends care based on knowing you from head to toe. This saves you money, as opposed to going to different specialists for different aches and pains, which costs more. If you should ever need care from a specialist, your primary care physician will refer you to one in your health plan's network. HMOs help their members receive quality care at reasonable prices.