The current study explored the preferences for and knowledge of weight-based terminology used in healthcare-related conversations, and descriptively compared the preferences of children, parents and healthcare professionals. In total, 86 children with overweight or obesity, 90 parents of children with overweight or obesity and 572 healthcare professionals indicated their preferences for 22 terms. When applicable, children and parents could indicate unfamiliarity with a term. Many children were unfamiliar with terms such as "adiposity"adipositas"" (93%), "BMI" (60%) and "morbid obesity" (53%). Children, parents and healthcare professionals disliked "fatadjective". All groups liked the terms "healthier weight" and "above a healthy weight". To conclude, children's, parents' and healthcare professionals' preferences for weight-based terminology are predominately congruent, except for "BMI". "BMI" is a popular term among healthcare professionals. It is recommended that healthcare professionals use terms that can be perceived as neutral or positive, such as "healthier weight", as this may contribute to a positive conversation which may lead to better compliance, and to avoid terms that can be perceived as judgmental, such as "fatadjective", as this may worsen the dialogue and relationship between families and healthcare professionals, and increase weight-based stigma. Healthcare professionals should be aware that children may be unfamiliar with some terms.