(1) An inflatable spheric or ovoid device used to retain tubes or catheters in, or provide support to, various body structures. (2) A distensible device used to stretch or occlude a viscus or blood vessel. (3) To distend a body cavity with a gas or fluid to facilitate its examination, dilate a structure, occlude a lumen, or create a space for a retroperitoneal, laparoscopic procedure. [Fr. ballon, fr. It. ballone, fr. balla, ball, fr. Germanic]