An autism spectrum disorder that does not meet the diagnostic criteria for either autism proper or Asperger's syndrome.

(medicine) Pneumonia not caused by one of the pathogens most commonly associated with the disease, such as Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

plural of atypical pneumonia

(pharmacology) Any of a group of antipsychotic drugs largely introduced after the 1970s and used to treat mental disorders.

plural of atypical antipsychotic