noun: Initialism of irritable bowel syndrome. [(pathology) A functional disorder causing the nerves and muscles of the large intestine to be oversensitive, leading to symptoms such as cramp, bloating, flatulence, diarrhoea and constipation.]
noun: Initialism of ichthyosis bullosa of Siemens. [(medicine, dermatology) A type of familial, autosomal dominant ichthyosis, a rare skin disorder.]