A small, rounded lump or mass of tissue, often found in the body, such as on the thyroid gland or in the lungs. The doctor discovered a nodule on her thyroid during the examination.
A small, rounded lump of mineral or rock, often found in sedimentary formations. Geologists found a nodule of iron ore embedded in the rock.
A small, rounded growth on the roots of certain plants, such as legumes, that contains nitrogen-fixing bacteria. The farmer noticed nodules on the roots of his pea plants, indicating healthy nitrogen fixation.