Final answer:
The rate of speed at which a piece of music is played is called the tempo. It defines how fast or slow the music piece should be executed, unlike meter, movement, or mood, which refer to the rhythm structure, sections of a piece, or emotional feel, respectively.
Step-by-step explanation:
The rate of speed at which a piece of music is played is known as its tempo. This term refers to the speed or pace of the music - essentially, how fast or slow the piece should be played. The tempo is typically indicated by various musical terms or metronome markings at the beginning of a piece of music, and it can be adjusted for expressive effect throughout the piece. While meter relates to the pattern of the beats or the rhythmic structure, movement refers to a section within a larger piece, and mood refers to the emotional feel of the piece, tempo specifically addresses the speed.