The word "lonely" describes a feeling of sadness because one is alone or isolated. It often conveys a sense of yearning for companionship or connection with others. Being lonely can involve physical loneliness (being by oneself) or emotional loneliness (feeling disconnected from others even when they are present).
The word "lonely" comes from the word "lone," which means solitary or by oneself, combined with the suffix "-ly," which is used to form adjectives. The term has its roots in the Old English word "ānlīc," meaning "one" or "single," and it has evolved over time to carry its current meaning associated with solitude in both a physical and emotional sense.