What is the medical terminology combining form meaning gallbladder?

Bile or gall is a bitter-tasting, dark green to yellowish brown fluid.

Bile Composition: Water - 85.0%, Bile salts - 10%, Coloring matter and mucus - 3%, Fats - 1%, Cholesterin - 0.3%, Inorganic salts - 0.7%.

Bilious is the Word you're looking for.
Chole

bile (Note: Chole plus cyst, meaning bladder, equals gallbladder;

chole plus doch, meaning duct, equals choledocho or common bile duct.)