'ASD' originates from English, specifically the phrase 'autism spectrum disorder', where 'autism' ultimately comes from Greek 'autos' meaning 'self', 'spectrum' comes from Latin 'spectrum' meaning 'image' or 'apparition', and 'disorder' comes from Old French 'desordre' meaning 'lack of order'.

'Autism' was used in early 20th-century psychiatric literature (from German 'Autismus') to describe withdrawal into the self; the clinical concept expanded through mid- to late-20th century and the compound phrase 'autism spectrum disorder' became the standard diagnostic label in DSM-5 (2013), from which the initialism 'ASD' is derived.

Initially, 'autism' described a state of withdrawal into oneself; over time the term evolved into the modern clinical meaning referring to a range of neurodevelopmental differences involving social communication and restricted, repetitive patterns of behavior.