1.Definition: being approximately average or within certain limits in e.g. intelligence and development

"A perfectly normal child", "Of normal intelligence", "The most normal person I've ever met"

2.Definition: conforming with or constituting a norm or standard or level or type or social norm; not abnormal

"Serve wine at normal room temperature", "Normal diplomatic relations", "Normal working hours", "Normal word order", "Normal curiosity", "The normal course of events"

3.Definition: forming a right angle

4.Definition: in accordance with scientific laws