What condition is indicated by a child's inability to gain weight and grow properly?

The condition characterized by a child's inability to gain weight and grow properly is known as failure to thrive. This term describes a pediatric syndrome where an infant or child does not gain weight or grow as expected, falling significantly below the established growth parameters for their age and sex.

Failure to thrive can result from a variety of factors, including inadequate caloric intake, chronic medical conditions, or psychosocial issues that may impair the child's growth and development. It is not merely a lack of weight gain; it also encompasses poor growth patterns over time and can be indicative of underlying health problems that require further investigation and intervention.

Other choices such as obesity, anorexia, and malnutrition relate to different issues around nutrition and weight. Obesity, for instance, is characterized by excessive weight gain rather than poor growth. Anorexia refers to a psychological condition leading to self-imposed starvation and is different from the physiological issues seen in failure to thrive. Malnutrition can lead to failure to thrive, but it is broader and includes inadequate nutrition regardless of weight gain, whereas failure to thrive specifically emphasizes the aspect of insufficient growth. Thus, the focus on growth and weight gain in children makes failure to thrive the most accurate and specific answer in this context.