Obumbrate is a relatively uncommon term which means to darken or overshadow something, or to cast a shadow upon. If you're looking for synonyms to make your writing more varied and interesting, there are several options to choose from. Some possible alternatives for obumbrate include obscure, eclipse, veil, shroud, conceal, mask, overshadow, cloak, and obstruct. Each of these words has a slightly different shade of meaning, so you may want to choose the one that best fits the context of your sentence. By using synonyms for obumbrate, you can add depth and complexity to your writing, making it more engaging and memorable for your readers.