| d-layer | (n) the lowest region of the ionosphere (35 to 50 miles up) that reflects low-frequency radio waves, Syn. D region |
| D-layer | n. the lowest region of the ionosphere (35 to 50 miles up) that reflects low-frequency radio waves. |
| Wood-layer | n. (Bot.) A young oak, or other timber plant, laid down in a hedge among the whitethorn or other plants used in hedges. [ 1913 Webster ] |