Bladder

n. [A-S. blædre, blæddre, Icel. blaðra, blaðra, Sw. blådra, Dan. blære, D. blaar, O. H. Ger. blâtara, the bladder in the body of animals, N. H. Ger. blatter, blister, pustule. The root is A-S. blāwan, O. H. Ger. blāhan, blājan, to blow, flare. Cf. Ger. blase, bladder, from blasen, to blow.]

1. (Anat.) A bag or sac in animals, which serves as the receptacle of some secreted fluid; as, the urinary bladder, the gall bladder;—applied especially to the urinary bladder, either within the animal, or when taken out and inflated with air.
2. Any vesicle or blister, especially if filled with air, or a thin, watery liquor.
3. (Bot.) A distended, membranaceous pericarp.
4. (Fig.) Any thing inflated, empty, or unsound. “To swim with bladders of philosophy.” Rochester.