Obumbration refers to the act of casting a shadow or to obscure something. There are several other words that can be used interchangeably with this term. For instance, the word 'eclipse' can be used to describe the covering of something by a shadow. In addition, the term 'obscure' can refer to something that is unclear or hard to understand, much like an obumbration. Similarly, 'veiling' can be used to describe the concealment of something behind a cover or a veil. 'Concealment' can also be used to describe the act of hiding something or making it hard to see. Finally, 'occlusion' can be used to describe the obstruction of something by another thing.