donation. 1  an act or instance of presenting something as a gift, grant, or contribution. 2  a gift, as to a fund; contribution.
A black or brown tongue typically is due to the overgrowth of bacteria that normally are present on the tongue. This, too, can be caused by the killing of some bacteria with antibiotics so other bacteria overgrow. But the most common cause of discoloration of the tongue is the overgrowth of a fungus. The most common fungus is called candida. But overgrowth of the candida fungus turns the tongue white. Infection with candida is called candidiasis, and when it happens on the tongue the condition is called thrush.
But as they grow, pigments from food, drinks, and possibly the bacteria or yeast themselves get caught in the papillae, dyeing the tongue a color. Most often that color is black, hence the name. But the tongue can also turn brown, yellow, green, or a variety of other colors. Certain lifestyle habits and conditions can make people more likely to develop black hairy tongue. Black hairy tongue is more common in men, people who use intravenous drugs, and those who are HIV-positive.