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.
Ma - But. Used with other words, e.g. lento ma non troppo, slow but not too slowly.
Nachtmusik - "Night music." A serenade.
Octave - The eighth tone above a given pitch, with twice as many vibrations per second, or below a given pitch, with half as many vibrations.