The Collaborative International Dictionary of English v.0.48:

Frankalmoigne \Frank`al*moigne"\, n. [F. franc free + Norm. F.
   almoigne alma, for almosne, F. aum[^o]ne. See Frank, a.,
   and Almoner.] (Eng. Law)
   A tenure by which a religious corporation holds lands given
   to them and their successors forever, usually on condition of
   praying for the soul of the donor and his heirs; -- called
   also tenure by free alms. --Burrill.
   [1913 Webster]

The Devil's Dictionary (1881-1906):

FRANKALMOIGNE, n.  The tenure by which a religious corporation holds
lands on condition of praying for the soul of the donor.  In mediaeval
times many of the wealthiest fraternities obtained their estates in
this simple and cheap manner, and once when Henry VIII of England sent
an officer to confiscate certain vast possessions which a fraternity
of monks held by frankalmoigne, "What!" said the Prior, "would you
master stay our benefactor's soul in Purgatory?"  "Ay," said the
officer, coldly, "an ye will not pray him thence for naught he must
e'en roast."  "But look you, my son," persisted the good man, "this
act hath rank as robbery of God!"  "Nay, nay, good father, my master
the king doth but deliver him from the manifold temptations of too
great wealth."