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Adenoidectomy - The surgical removal of the adenoids.

Antibiotic - A drug used to treat bacterial infections. The original definition of an antibiotic was a substance produced by one microorganism that selectively inhibits the growth of another microorganism. However, wholly synthetic antibiotics (usually chemically related to natural antibiotics) have since been produced that accomplish comparable tasks.

Apnea - The absence of breathing (respirations). There are three forms of apnea: blockage of the airway, cessation of respiratory effort (usually brain-related and referred to as "central"), and a combination of airway blockage and central apnea.

Attention-deficit hyperactivity disorder (ADHD) - ADHD refers to a family of related chronic neurobiological disorders that interfere with an individual's capacity to regulate activity level (hyperactivity), inhibit behavior (impulsivity), and attend to tasks (inattention) in developmentally appropriate ways. The core symptoms of ADHD include an inability to sustain attention and concentration, developmentally inappropriate levels of activity, distractibility, and impulsivity. Children with ADHD have functional impairment across multiple settings including home, school, and peer relationships. ADHD has also been shown to have long-term adverse effects on academic performance, vocational success, and social-emotional development. Children with ADHD experience an inability to sit still and pay attention in class and the negative consequences of such behavior. They experience peer rejection and engage in a broad array of disruptive behaviors. Their academic and social difficulties have far-reaching and long-term consequences. These children have higher injury rates. As they grow older, children with untreated ADHD, in combination with conduct disorders, experience drug abuse, antisocial behavior, and injuries of all sorts. For many individuals, the impact of ADHD continues into adulthood.

Audiogram - A test of hearing at a range of sound frequencies.