There are several antonyms for the word "heightenings". The first antonym is "reductions," which refers to the act of decreasing or lowering something. Another antonym is "diminishments," which refers to the act of making something smaller or less significant. "Lessenings" is also an antonym for "heightenings," and it refers to the act of decreasing the amount or intensity of something. "Lowerings" is another antonym, and it refers to the act of bringing something down to a lower level. Finally, "lowerings" can also mean to decrease the value or status of something. Overall, these antonyms help to provide a clearer understanding of the opposite meaning of "heightenings".