A Dictionary of Music and Musicians/Cantabile
CANTABILE, i.e. singable, a direction placed against an instrumental phrase when it is to be 'sung' with feeling. Beethoven does not often use it, and when he does it is always with special intention, as in the 2nd subject of the Larghetto of the B♭ Symphony, and in the semiquaver figure in the working out of the first movement of the 9th Symphony:—
He has before marked it 'expressivo'—but now it is as if he said 'you may see no special melody in this group, but I do, and will have it played accordingly.'