loam Syllabification: (loam)Pronunciation: /lōm/Definition of loam noun a fertile soil of clay and sand containing humus. Geology a soil with roughly equal proportions of sand, silt, and clay. a paste of clay and water with sand, chopped straw, etc., used in making bricks and plastering walls. Derivatives loaminess noun loamy adjective Origin: Old English lām 'clay'; related to Dutch leem and German Lehm, also to lime1loam in other Oxford dictionaries Definition of loam in the British & World English dictionary