Describes a person who's behavior resembles that of one who fits somewhere within the pervasive developmental disorder (PDD) spectrum, such as a person with autism or Aspberger's syndrome. PDD is marked by impaired social interaction skills.
Dr. Poindexter is kind of spectrumish, but he's an awesome dermatologist in spite of his lousy bedside manner.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).