A brief sudden change in a normally constant quantity: a pulse of current; a pulse of radiation. b. Any of a series of intermittent occurrences characterized by a brief sudden change in a quantity.
Some pregnant women experience a metallic taste in their mouth during the early stages of pregnancy, because of the hormone changes. It's also fairly common to crave certain foods, or go off certain foods, and have a heightened sense of smell. Learn more about the signs and symptoms of pregnancy.
This type of taste in the mouth is sometimes the result of heavy metal toxicity. Particularly, mercury from silver amalgam fillings in the teeth, but it could be some other source of metal like lead, copper etc. New pipes in the house, an unknown source of lead etc., eating fish or food out of the can. Cookware.