The phrase "less and less" can be used to indicate a gradual reduction in something over time. There are several synonyms for this phrase that convey a similar meaning. One such phrase is "decreasingly," which suggests that something is becoming smaller or less frequent. Another synonym is "diminishingly," which conveys a sense of something gradually becoming less significant or important. "Slowly but surely," is another phrase that can be used to describe a gradual reduction in something over time. Other synonyms for "less and less" include "gradually declining," "diminishingly," and "incrementally decreasing." All of these phrases can be used to describe a gradual decrease in something over time.