Loneliness is an experience known to all human beings. Inherent in the need to belong, it is regarded as an epidemic in modern society, a public health problem that needs to be addressed from a variety of perspectives, given its physical, mental and social consequences. Adolescence is a particularly vulnerable stage for experiencing feelings of loneliness, which are a significant factor for adolescent health and quality of life and , as such, it is relevant to nursing care. The purpose of this article is to analyze the concept of loneliness during adolescence through the method proposed by Walker and Avant, which is a strategy for examining the characteristics that define a concept and its attributes. An understanding of this phenomenon will make it possible to propose strategies for prevention and intervention, and to guide care for this age group.