indicating a lack of maturity

of or relating to infants or infancy

being or befitting or characteristic of an infant

a hereditary disorder of lipid metabolism occurring most frequently in individuals of Jewish descent in eastern Europe; accumulation of lipids in nervous tissue results in death in early childhood

a rare but serious syndrome of childhood characterized by withdrawal and lack of social responsiveness or interest in others and serious linguistic deficits

an abnormal state in which development has stopped prematurely

an acute viral disease marked by inflammation of nerve cells of the brain stem and spinal cord