Aggression
An aggression is an unprovoked attack or harmful action against another. (noun)
An example of an aggression is a dog barking and chasing after another dog in an effort to attack.
Aggression refers to the practice of being offensive or prone to attacking others. (noun)
An example of someone who is prone to bouts of aggression would be someone who is routinely starting fights.  Aggression as defined by yourdictionary.com
See also Agression defined on onelook.com

Aggressive
Behaving in an angry or rude way that shows you want to fight, attack, or argue with someone. Aggressive as defined by the Macmillan Dictionary.

Autism
Autism is a condition that develops early in childhood before aged 3 and that affects development, causing problems with social interactions and communication. (noun)  Autism as defined by yourdictionary.com
See also Autism defined on onelook.com

Autism Spectrum
Different people with autism can have very different symptoms. Health care providers think of autism as a "spectrum" disorder, a group of disorders with similar features. One person may have mild symptoms, while another may have serious symptoms. But they both have an autism spectrum disorder.

Currently, the autism spectrum disorder category includes:

Autistic disorder (also called "classic" autism)

Asperger syndrome

Pervasive Developmental Disorder Not Otherwise Specified (or atypical autism)

In some cases, health care providers use a broader term, pervasive developmental disorder, to describe autism. This category includes the autism spectrum disorders above, plus Childhood Disintegrative Disorder and Rett syndrome.  Autism Spectrum as defined by the National Institute of Child Health & Human Development

Autistic
adjective: characteristic of or suffering from autism  Autistic as defined on onelook.com

Savant
A savant is a scholar or learned person. (noun) Someone who is considered a scientific genius is an example of a savant.  Savant as defined in yourdictionary.com

Seizures
Clinical or subclinical disturbances of cortical function due to a sudden, abnormal, excessive, and disorganized discharge of brain cells. Clinical manifestations include abnormal motor, sensory and psychic phenomena. Recurrent seizures are usually referred to as EPILEPSY or "seizure disorder."  Seizures as defined by medicaldictonaryweb.com
See also Seizures defined on onelook.com

Special Needs Children
"Special Needs" is an umbrella underneath which a staggering array of diagnoses can be wedged. Children with special needs may have mild learning disabilities or profound cognitive impairment; food allergies or terminal illness; developmental delays that catch up quickly or remain entrenched; occasional panic attacks or serious psychiatric problems. The designation is useful for getting needed services, setting appropriate goals, and gaining understanding for a child and stressed family. Special Needs Children as defined in about.com

Violence
Violence is the use of physical force intended to harm. (noun) An example of violence is when you punch someone or when you shoot someone.  Violence as defined by yourdictionary.com