The term developmental delay can refer to: Global developmental delay, an umbrella term used when children are significantly delayed in two or more areas of development Specific developmental disorder, a classification of disorders characterized by delayed development Intellectual disability, generalized neurodevelopmental disorder characterized by significantly impaired intellectual and adaptive functioning Developmental disability, diverse group of chronic conditions, comprising mental or physical impairments that arise before adulthood Pervasive developmental disorder, a classification of disorders by delays in basic functions

Reference
Wiki: Developmental delay