geode vs sac

geode

• A nodule of stone having a cavity lined with mineral or crystal matter on the inside wall. 

sac

• A bag or pouch inside a plant or animal that typically contains a fluid. 

• A sacrifice. 

• The privilege, formerly enjoyed by the lord of a manor, of holding courts, trying causes, and imposing fines; now used only in the phrase sac and soc or soc and sac. 

• To sacrifice.