The verb "richen" is often used to describe making something richer, fuller, or more substantial. However, there are different ways to express this concept in language. One way is to use the verb "enrich," which means to improve the quality or value of something by adding something else to it. Another synonym for "richen" is "strengthen," which conveys the idea of making something stronger or more robust. Similarly, the verb "thicken" can be used to describe making something denser or more substantial. Lastly, the verb "intensify" can also be used as a synonym for "richen," conveying the idea of making something more intense or powerful.