LYRIC or LYRICS (singular or plural)

[ckcgordon]

The following sentences are taken out from a voice-over: The film featured the song Born To Be Wild which contained the lyric "heavy metal thunder". From that point on, thundering rock and roll was referred to as "heavy metal". I don't understand why the singular noun "lyric" is used. My dictionary says "lyric" means a poem. When we want to refer to the words of a song, we say "lyrics".

For your information, the whole voice-over is given below:
Psychedelic rock flourished during the halcyon days of the psychedelic 60s. Its counterculture sound was a perfect fit to America's cultural revolution. In 1968 the hottest counterculture movie was Easy Rider. The film featured the song Born To Be Wild which contained the lyric "heavy metal thunder". From that point on, thundering rock and roll was referred to as "heavy metal".

If you have time, you can listen to it on the internet: YouTube - Steppenwolf-Born To Be Wild

[bianca]

According to merriam webster online:
lyric means:

1. a lyric composition; specifically : a lyric poem (with songlike quality)
2 : the words of a song -- often used in plural (lyrics)

So, you have answered your own question. "Heavy metal thunder" is referred to as a lyric poem (a song). If you refer to its content, or words, then you refer to the song's lyrics. (What are the lyrics of this song?)

Also:

the lyric is...
the lyrics are...

[ckcgordon]

Thanks for your prompt reply, Bianca. I'm sorry I don't quite understand why you said: "heavy metal thunder" is referred to as a lyric poem (a song) . "heavy metal thunder" is the WORDS CONTAINED in the song "Born to Be Wild"! Anyway, I was wondering if there is any difference between the following expressions:

(1) The song contains the lyric "heavy metal thunder".
(2) The song contains the lyrics "heavy metal thunder".

Which one is correct? Or both are correct?