Which term refers to the instruction to hold a note or a chord for its full duration?

The term that refers to the instruction to hold a note or a chord for its full duration is "tenuto." When a note is marked with tenuto, it indicates that the performer should sustain the note for its whole value, which adds expressive depth to the music. This instruction essentially emphasizes the note, allowing it to resonate completely before moving on to the next note or chord.

In contrast, staccato means to play the note shorter and detached, creating a different character in the music. Marcato also instructs to play notes with a marked emphasis, but it doesn’t specifically denote holding the note for its full value as tenuto does. Fermata, while it signifies to hold a note longer than its written duration, is typically used to indicate a pause and allows for a subjective duration beyond what is notated, thus not strictly instructing to play it for its complete length in the regular sense.