Heart burn : It is the condition when the cardiac sphincter fails to close completely and acidic gastric juice is squeezed into the oesophagus. The acid present in the gastric juice irritates the cells in the oesophagus and the burning sensation in the chest can extend to the neck, throat.
Lactose intolerance : It is the inability of adults and children to digest lactose, a sugar found in milk and to a lesser extent dairy products, causing side effects.
Diphyodont is the condition of having two set of teeth during the life of an organism. For example : humans are diphyodont as they have two set of teeth namely temporary milk or deciduous teeth which are replaced by permanent or adult teeth.