The term<unk>  (or "developmental delays") is used to describe the condition where a child does not reach one of these stages at the expected age. However, in most cases, a wide variety of ages can be considered normal, and not a cause for medical concern.<unk> s are often measured using percentiles, and for many<unk> s a value between the 5th and 95th percentile does not require intervention, though values towards the edges of that range can be associated with other medical conditions.
Delayed milestone
Physical dependence
Hysteresivity
Abnormality 
Pragmatic language impairment
Impulsivity
Language delay
Interlanguage links