Wolfram Alpha recently announced the addition of song lyrics to its powerful search engine, and Siri, piggybacking on the service, can now show you lyrics for your favorite songs in addition to the all the other cool things it can do.
To get lyrics for a song, open Siri by pressing and holding the home button, and ask “What are the lyrics to <song name>”. Siri takes more time than usual to respond to this query, but you should get the lyrics eventually. For certain queries, though, I found Siri to fall back to a web search.
Wolfram Alpha’s lyrics search is powered by LyricFind, which boasts having licenses from over 2000 music publishers, so you should be able to find lyrics for almost all songs via Siri.
See also: 10 Siri And Wolfram Alpha Tricks