Dictionary:

shogunate

  (shō'gə-nĭt, -nāt')

The government, rule, or office of a shogun.

The noun has one meaning:

Meaning #1: a form of government in which the ruler is an absolute dictator (not restricted by a constitution or laws or opposition etc.)
  Synonyms: dictatorship, absolutism, authoritarianism, Caesarism, despotism, monocracy, one-man rule, Stalinism, totalitarianism, tyranny