Diagonalwise is a descriptive word that portrays the notion of moving diagonally. This word is popularly used to describe a particular direction that is neither vertical nor horizontal. There are several synonyms that can be used in place of diagonalwise such as obliquely, slantingly, or askew. These words all imply a diagonal direction. Another synonym for diagonalwise is catty-corner, which is a more colloquial term. Other words like angularly, crookedly, and skewedly can also be used interchangeably. Whether you use diagonalwise or any of its synonyms, it still conveys the same meaning of something moving on a diagonal.