Loneliness in childhood and adolescence is currently measured using questionnaires and checklists. The most used questionnaires for youth are psychometrically limited, partly due to the absence of the young person's voice from the measurement development process. Given this gap in the literature, the current study explored primary-school aged children's understanding and experiences of loneliness, providing new information about the experience of loneliness in childhood to better inform conceptualisation and measurement of loneliness in children. Interviews took place during the COVID pandemic and were conducted with six Year 4 and 5 children (aged 8-10 years) and analysed using hybrid thematic analysis. Findings fit with existing conceptualisations of social and emotional loneliness and provide novel perspectives on solutions, the importance of play, and children's perceptions of the adult experience. Directions for future research, and the impact after COVID are discussed.