gister--prophetes.ai

† ˈgister Obs. rare.
  Also 7 geaster.
  [Aphetic form of agistor: in sense 2 prob. f. gist v. + -er¹.]
  1. = agistor.

1483 Cath. Angl. 157/1 A Gister, agistator.

2. A cow, etc. feeding on hired pasture.

1641 [see gist n.²].

Oxford English Dictionary