linguisticsgirl.com: ... In my mind, grammatical *form**(what a word looks like) is clearly separate from grammatical function (what a word does). From ODO: 2.1. Any of the ways in which a word may be spelled, pronounced, or inflected 4.2. [count noun] A set order of words; a formula:
When Michael J. Fox played 'Johnny B. Goode' as Marty McFly in 'Back to the Future' in 1985, he was just aping Chuck Berry's classic fretwork for the camera. (Along with some Jimi Hendrix, Eddie Van Halen and Pete Townsend guitar moves thrown in for good measure.) Today, Fox can really play the song.
The 1989 movie imagined a future that, in some cases, became reality. Michael J. Fox's character, Marty McFly, traveled from the 1980s to a future where energy is easy and cheap. It might feel like just yesterday to some, but the movie Back to the Future II came out nearly 26 years ago.