LEXICAL PART OF SPEECH:

• Lexicon: alphabetic arrangement of words and their definitions. A term often used to describe the list of allowable words for a speech recognition system.
  
  
• Lexical Part of Speech: A restricted inventory of word-type categories which capture generalizations of word forms and distributions ("dog" and "cat" are nouns and animals).
  
  
• Part of Speech (POS): noun, verb, adjective, adverb, interjection, conjunction, determiner, preposition, and pronoun.
  
  
• Proper Noun: names such as "Velcro" or "Spandex". Pose a very challenging problem for speech recognition because of the lack of pronunciation rules (e.g., "Nyugen", "Sorbet").
  
  
• Open POS Categories:
  
  

  Tag	Description	Function	Example
  N	Noun	Named entity	cat
  V	Verb	Event or condition	forget
  Adj	Adjective	Descriptive	yellow
  Adv	Adverb	Manner of action	quickly
  Interj	Interjection	Reaction	Oh!

  
  
  
• Closed POS Categories: some level of universal agreement on the categories (e.g, conjunction, determiner, preposition).
  
  
• Penn Treebank: the LDC's Penn Treebank is one of the most ambitious projects to date in which large amounts of data have been categorized.
  
  
• Wordnet: Princeton's Wordnet is another very important and ambitious project to develop an on-line lexical reference system.