anacrotic
/ˌænəˈkrɒtɪk/Definitions
1. noun
relating to or characterized by a gradual decrease in intensity, especially in the context of a musical phrase
“The anacrotic section of the symphony was a beautiful example of musical dynamics.”
2. adjective
having or characterized by a gradual decrease in intensity or strength
“The anacrotic pattern of the earthquake’s seismic waves was a key factor in understanding the disaster.”