Probably Middle English 'kidnei' (belly-egg), describing the organ's shape — uniquely displaced the Germanic word 'nere.'
Either of a pair of bean-shaped organs in the abdominal cavity that filter blood, remove waste, and regulate fluid balance.
From Middle English 'kidnei,' of uncertain ultimate origin. The second element '-nei' likely comes from Old English 'ǣg' (egg), referring to the organ's egg-like shape. The first element 'kid-' is debated — it may come from Old English 'cwið' or 'cwiþ' (womb, belly), making the compound originally mean 'belly-egg' or 'womb-egg,' a vivid description of the organ's shape and location. The word replaced the earlier Old English 'nēre,' which is cognate
The word 'kidney' likely means 'belly-egg' — a compound of Old English elements for 'womb' and 'egg,' describing the organ's ovoid shape nestled in the abdomen. This poetic native name displaced the older Old English 'nēre,' whose cognates survive in German 'Niere' and Dutch 'nier.' English is the only Germanic language