The Collaborative International Dictionary of English v.0.48:

Pensionary \Pen"sion*a*ry\, n.; pl. Pensionaries. [Cf. F.
   pensionnaire. Cf. Pensioner.]
   1. One who receives a pension; a pensioner. --E. Hall.
      [1913 Webster]

   2. One of the chief magistrates of towns in Holland.
      [1913 Webster]

   Grand pensionary, the title of the prime minister, or or
      president of the Council, of Holland when a republic.
      [1913 Webster]