Diminishingly is a term that describes something that is decreasing in size, quantity, or quality. There are many synonyms for this word that can be used to convey the same meaning. Some common synonyms include dwindlingly, decliningly, decreasingly, and gradually. All of these words imply a gradual reduction, whether it be in the amount of something or the strength or power of it. Other synonyms include waning, ebbing, and fading, which suggest a more gradual decrease in intensity. However, all of these words are effective in describing something that is becoming smaller or weaker over time.