Which term indicates a stressed note in music?

The term that indicates a stressed note in music is "Accent." When a note is accented, it is played with greater emphasis than the surrounding notes, creating a distinct prominence in the musical phrase. Accents can be notated in various ways, such as using symbols above or below the note, and they help to shape the rhythm and dynamics of a piece. By drawing attention to specific notes, accents contribute to the overall expression and interpretation of the music.

The other terms do not indicate stressed notes. "Ad libitum" refers to a performance indication that allows the performer some degree of freedom to vary the tempo or to omit certain parts, which does not pertain to stressing specific notes. "Agitato" is a term used to indicate a restless or agitated character in the music, influencing the mood rather than emphasizing particular notes. "Alla," often seen in phrases like "alla breve," refers to a style or manner of playing or singing and does not specifically denote any stress on individual notes.