Which term indicates a gradual slowing down in music?

The term that indicates a gradual slowing down in music is "ritardando." This term is derived from the Italian word "ritardare," which means to slow down. In musical notation, ritardando is used to instruct musicians to decrease the tempo gradually, allowing for a more expressive and relaxed conclusion to a section or piece. It creates a feeling of relaxation or anticipation, enhancing the emotional delivery of the music.

Ritardando is often employed effectively at the end of phrases or movements, creating a dramatic effect as the tempo slows. This technique is fundamental in conveying the desired emotional nuance in a performance, making it an important term for musicians to understand and implement.

Other terms mentioned, such as "colla," do not pertain to slowing down music but instead relate to bringing a musical line together or following another part. "Accent" denotes emphasis placed on a particular note or chord, indicating it should be played louder or with more force. "Animato" suggests playing in a lively and animated manner, which is quite the opposite of slowing down. Thus, ritardando is the accurate choice for indicating a gradual decrease in tempo.