There are a number of different definitions of the term “assisted living," but all are fairly similar.
The definition used by the United States Administration on Aging (AOA) is facilities that offer "housing alternatives for older adults who may need help with dressing, bathing, eating and toileting, but do not require the intensive medical and nursing care provided in nursing homes. Assisted living facilities may be part of a retirement community, nursing home, senior housing complex or may be stand-alone."
In addition, the AOA goes on to state that licensing may differ depending on the state in which the facility is located.
For more information on assisted living, visit http://www.extension.org/pages/Assisted_Living_Facilities.