lemon, (Citrus lemon), small tree or spreading bush of the rue family (Rutaceae) and its edible fruit. Lemon juice is a characteristic ingredient in many pastries and desserts, such as tarts and the traditional American lemon meringue pie. Lemons are a popular fruit that people use in small quantities to add flavor to food. However, they rarely consume them alone due to their intense, sour taste. Lemons give flavor to baked goods, sauces, salad dressings, marinades, drinks, and desserts, and they are also a good source of vitamin C.
