Melody

Webster's Dictionary of the English Language

·noun The air or tune of a musical piece.

II. Melody ·noun A sweet or agreeable succession of sounds.

III. Melody ·noun A rhythmical succession of single tones, ranging for the most part within a given key, and so related together as to form a musical whole, having the unity of what is technically called a musical thought, at once pleasing to the ear and characteristic in expression.