Knowledge is Power!
Half step - The interval from one pitch to the immediately adjacent pitch, ascending or descending, e.g.
Impressionism - A musical movement of the late 19th and early 20th centuries. Inspired by the French impressionist painters, the movement had its impetus in the music of Debussy and Ravel.
Key signature - The sharps or flats placed at the beginning of the staff to denote the scale upon which the music is based.
La - In solmization, the sixth degree of the major scale. Also, the first degree of the relative minor scale, e.g. a is the sixth degree, or la, in the C major scale and the first degree of the a-minor scale.
Maestoso - Majestically.