noun (n)

• a small unit serving as part of or as the nucleus of a larger political movement(noun.group)

  Synonym:
  cell
  

  source: wordnet30
• a nucleus of military personnel capable of expansion(noun.group)

  source: wordnet30
• The framework or skeleton upon which a regiment is to be formed; the officers of a regiment forming the staff.(noun)

  source: webster1913