What is the definition or description of: delayed development?

Developmental delay: When your baby and child are expected to do certain things is behind schedule. For instance, most kids are walking by 12-15 months. If your child is 18 months and not walking, this skill is delayed. As pediatricians, we are watching many different areas of development to see if child is progressing as they are expected to. We're watching motor skills, speech development and how they act!