The American Heritage® Dictionary of the English Language, 4th Edition
n. A pervasive developmental disorder characterized by severe deficits in social interaction and communication, by an extremely limited range of activities and interests, and often by the presence of repetitive, stereotyped behaviors.
n. Bio-neurological disorder that is observable in early childhood with symptoms of abnormal self-absorption, characterised by lack of response to other humans and by limited ability or disinclination to communicate and socialize.
the GNU version of the Collaborative International Dictionary of English
n. a mental disorder characterized by inability to engage in normal social interactions and intense self-absorption, and usually accompanied by other symptoms such as language dysfunctions and repetitive behavior.
n. behavior showing an abnormal level of absorption with one's own thoughts and disregard for external realities.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. (psychiatry) an abnormal absorption with the self; marked by communication disorders and short attention span and inability to treat others as people
Word Usage
"The word 'autism' comes from the Greek word 'autos', meaning 'self'."