This MacOS application displays the lyrics for the currently-playing track in iTunes or Spotify.
There are many like it. This one is mine.
If the track does not have lyrics, then they are downloaded from lyrics.wikia.com if possible.
There is also a command to bulk-download the lyrics for all of the songs in the selected playlist.
Fonts, colors and opacity are adjustable, and you can edit the lyrics directly in the window.
It can also optionally display a notification at the bottom of the screen when the track changes, By default, it displays the track info shortly after the track starts, and shortly before it ends, music video style.