nodule

Meanings

1. 1
   noun

   a small rounded lump, knot, or mass in tissue, rock, or another material

   The geologist split the shale and found a hard mineral nodule inside.

2. 2
   noun

   medicine: a small abnormal or distinct rounded growth in body tissue

   The ultrasound showed a small thyroid nodule that required monitoring.

3. 3
   noun

   botany: a small swelling on a plant, especially one on a root containing nitrogen-fixing bacteria

   Each root nodule housed bacteria that supplied the plant with usable nitrogen.

Borrowed from Latin nodulus, 'small knot,' a diminutive of nodus, 'knot.' Geology, medicine, and botany all use the word for a compact rounded mass: a mineral concretion, a tissue growth, or a swelling on a plant root.

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