What is "immovable feasts"

Immovable \Im*mov"a*ble\, a.

1. Incapable of being moved; firmly fixed; fast; -- used of material things; as, an immovable foundation.

   Immovable, infixed, and frozen round.
   --Milton.

2. Steadfast; fixed; unalterable; unchangeable; -- used of the mind or will; as, an immovable purpose, or a man who remains immovable.

3. Not capable of being affected or moved in feeling or by sympathy; unimpressible; impassive.
   --Dryden.

4. (Law.) Not liable to be removed; permanent in place or tenure; fixed; as, an immovable estate. See Immovable, n.
   --Blackstone.

   Immovable apparatus (Med.), an appliance, like the plaster of paris bandage, which keeps fractured parts firmly in place.

   Immovable feasts (Eccl.), feasts which occur on a certain day of the year and do not depend on the date of Easter; as, Christmas, the Epiphany, etc.