The term 'neck line' can refer to three different things. The first is a MANE, which is the long, thick hair that grows on the neck of certain animals, such as horses and lions. The second is a LASSO, which is a rope or cord used for catching animals or people by looping it around their necks. The third is a FRET, which is a narrow band or strip of wood or metal placed across the fingerboard of a stringed instrument, such as a guitar, to shorten the length of the strings and produce different notes.