The term frailty has been used for many years, both in everyday and academic language. It is a term that appears, on the surface, to be simple enough in its meaning, yet it has been used in a variety of ways to describe both people and a condition that applies to people. Moreover, little conceptual thought has gone into the nature of frailty and the factors that might affect it. This paper presents a definition of frailty: frailty occurs when there is diminished ability to carry out the important practical and social activities of daily living. It also presents a conceptualization of frailty that specifies its basic components, the categories of factors that contribute to it, and its relationship to closely related concepts.