Ascending and Descending are antonyms. This shows that whatever meaning you have for ascending; the opposite will be descending. These two words are used mostly in mathematics or any subject area that deals with measurement and classification. Whenever ascending is used, it means different items are to be classified or arranged based on their size, such that they are arranged as they increase in size. For example, counting from 1-100 is in ascending order, i.e., you are starting from the least to the highest.
Whenever the word Descending is used, it means you are to arrange items as they decrease in size or amount. For example, counting from 100- 1 is in descending order. Ascending is a verb which means to move upward, to soar. While descending is the exact opposite of ascending, i.e., to move downward. Ascending is used in many professions to show the upward movement of an object while descending describes the downward movement of an object.