Loneliness can be defined as a feeling of dissatisfaction with one’s social connections with others. The feeling is often described as complex because a person who is lonely may also experience anxiety, frustration, anger, and helplessness among other emotions. Emphasis is placed on a person’s subjective perception of their current relationships and their perceived need for changes or improvements. Loneliness is a common human experience. Many individuals can identify a time when they felt lonely. This entry explores the importance of loneliness in human social interactions. While marriage, family, and coupling relationships may serve as a defense against loneliness, they cannot entirely protect husbands, wives, lovers, and children from experiencing loneliness. This entry distinguishes loneliness from other related constructs and explores its manifestations, consequences, causes, ...