Final answer:
A song that is created by writing new lyrics to a preexisting melody is called a cover.
Step-by-step explanation:
When a musician or band decides to perform a popular song, but wants to put their own spin on it, they may choose to create a cover. A cover is essentially a new version of an existing song, with different lyrics that are written to fit the original melody.
This allows the artist to express their own unique style and interpretation of the song, while still paying homage to the original composer and melody. Covers can be found in various genres of music, from pop and rock to jazz and classical, and can often become popular in their own right, as fans connect with the new lyrics and performance style.
In short, a cover is a fresh take on a familiar tune, created by writing new lyrics to an existing melody.