A toadstool is a mushroom, especially one that's poisonous or inedible. When you see a bright red mushroom with white spots in a fairy tale or fantasy illustration, that's the classic toadstool: beautiful to look at but dangerous to eat.

People use the word as a warning for mushrooms they think might be harmful. Experienced mushroom foragers can tell safe mushrooms from poisonous ones, but it takes years of study. Many deadly poisonous mushrooms look almost identical to edible ones.

People sometimes use mushroom and toadstool interchangeably, but toadstool usually suggests something you shouldn't eat. When you're hiking and spot mushrooms growing under trees or on rotting logs, it's safest to treat them all as toadstools unless you're with an expert who knows exactly what they are. Even small amounts of certain toadstools can make people severely ill.

The word also appears in children's stories and games, where toadstools serve as furniture for fairies or houses for gnomes, their spotted caps making perfect magical umbrellas or tables in imaginary forests.