As a singular noun:
- A piece of music or poem meant to be sung.
- The words of a song or poem, especially when expressing personal emotions.
As a plural noun:
- The words or verses of a song, especially when considered together.
- A collection of poems or songs, especially on a particular theme or by a particular author.
Examples:
- _"He wrote the music and lyrics for the new musical."_ (in the singular sense)
- _"The lyrics were simple but powerful."_ (in the plural sense)