noun
decrescendo
Musical term indicating a gradual decrease in loudness. Used in scores and musical instruction.
from Italian
このパッセージはデクレッシェンドで演奏してください。
Please play this passage with a decrescendo.
クレッシェンド means a gradual increase in loudness, the opposite of デクレッシェンド.
ディミヌエンド is a near-synonym also meaning a gradual decrease in loudness; デクレッシェンド is more common in Japanese music terminology.
Borrowed from Italian 'decrescendo', a musical term meaning 'decreasing'.