Which term indicates an immediate slowing of the tempo?

The term that denotes an immediate slowing of the tempo is "Ritenuto." This term instructs musicians to reduce the tempo suddenly and is often used to create a dramatic effect in the music. It typically signals that the music should be played more slowly and can often be found in passages where the composer wants to emphasize a particular moment or phrase.

In contrast to ritenuto, "Ritardando" refers to a gradual slowing down over a longer span of time rather than an immediate change. A "Fermata" indicates a pause on a note or rest, while "Presto" refers to a very fast tempo, so these terms are unrelated to slowing down the music. Understanding these terms can help students interpret scores accurately and apply the appropriate tempo changes while performing.