What does nat. means in music?

The abbreviation "nat." in music stands for natural. It is used in music notation to indicate that a note should be played at its natural pitch, without any alterations. This is in contrast to the terms "sharp" and "flat", which indicate that a note should be played a half step higher or lower than its natural pitch, respectively.

The natural sign (♮) is used to cancel out a sharp or flat, restoring the note to its natural pitch. It is also used to indicate that a note should be played in its natural state, without any vibrato or other embellishments.

In some cases, the term "nat." may also be used to refer to the submediant, which is the sixth degree of the scale. This is because the submediant is often used as a resting point or point of resolution in a piece of music.