Question, is Rock and Roll, too "Broad" a term?

[Swish]

After watching and re-watching the HBO RnR Hall of fame 25th Anniversay special its easy to point out all the genres, sub-genres and legends omitted, missed, left out. I know we didn't see every performance nor the entire show BUT one thing is obvious, RnR means a great many different things to a great many different people and artists. What's your definition? To my knowledge, Rock and Roll was a term coined by jump blues piano players where in the bass rocked on the pedal and the right hand rolled or trilled some octave's higher. A classic example, the piano work on Big Joe Turner's "Shake Rattle and Roll".

Is there a definition? Does it need to be re-examined in "post splinter" popular music? Just askin'....

Worf

When I was a young pup, the genres didn't really matter to me and were summarily ignored. I never considered Jethro Tull 'progressive', but I remember that term was used to critique 'Thick as a Brick' when it was released way back when. I certainly knew the blues when I heard it, ditto country rock, folk, and the like, but rock was a huge amalgamation to me until I went off to college and caught 'the new wave'. Things seemed to spiral out of control soon after that, with punk, post-punk, prog, glam rock...it's a dizzying list. Check out this list that could be all-encompassing, most of which I wouldn't know if it bit me in the hind quarters:

* 2 Tone
* Acid rock
* Alternative dance
* Alternative metal
* Alternative rock
* Anatolian rock
* Art punk
* Art rock
* Avant-garde metal
* Baroque pop
* Beat
* Bisrock
* Black metal
* Blackened death metal
* Blues-rock
* Brazilian rock
* Britpop
* Bubblegum pop
* C86
* Canterbury sound
* Cello rock
* Celtic punk
* Celtic metal
* Celtic rock
* Chicano rock
* Christcore
* Christian punk
* Christian rock
* Christian metal
* Christian ska
* Coldwave
* Comedy rock
* Country rock
* Cowpunk
* Crossover thrash
* Crunkcore
* Crust punk
* Cuddlecore
* Dance-punk
* Dance-rock
* Dark cabaret
* Darkwave
* Death 'n' roll
* Deathcore
* Deathgrind
* Death metal
* Death rock
* Doom metal
* Dream pop
* Dunedin sound
* Electric blues
* Electric folk
* Electro Punk
* Electronic rock
* Emo
* Experimental rock
* Folktronica
* Folk rock
* Folk metal
* Folk punk
* Freakbeat
* Funk metal
* Funk rock
* Garage rock
* Garage punk
* German rock
* Glam metal
* Glam punk
* Glam rock
* Goregrind
* Gothic metal
* Gothic rock
* Grebo
* Grindcore
* Groove metal
* Group Sounds
* Grunge
* Gypsy punk
* Hatecore
* Hard rock
* Hardcore punk
* Heartland rock
* Heavy metal
* Horror punk
* Indie pop
* Indie rock
* Indorock
* Industrial folk song
* Industrial metal
* Industrial rock
* Instrumental rock
* Iranian rock
* J-ska
* Jam rock
* Jangle pop
* Jazz rock
* Jersey Shore sound
* Krautrock
* Latin rock
* Lo-fi
* Lovers rock
* Madchester
* Manguebeat
* Manila Sound
* Mathcore
* Math rock
* Medieval folk rock
* Medieval metal
* Melodic black metal
* Melodic death metal
* Melodic hardcore
* Metalcore
* Mod
* Mod revival
* Nardcore
* Nazi punk
* Neue Deutsche Welle
* Neo-classical metal
* Neo-folk
* Neo-Medieval music
* Neo-prog
* Neo-psychedelia
* New prog
* New Romantic
* New wave
* Nintendocore
* Noisecore
* Noise pop
* Noise rock
* No wave
* Nu metal
* Nu-folk
* Oi!
* Ostrock
* Pagan rock
* Paisley underground
* Pinoy rock
* Pirate Metal
* Pop punk
* Pop rock
* Pornogrind
* Post-punk
* Post-punk revival
* Post-hardcore
* Post-grunge
* Post-metal
* Post-rock
* Power pop
* Power metal
* Power violence
* Progressive folk
* Progressive metal
* Progressive rock
* Protopunk
* Power pop
* Psychedelic rock
* Psych-Folk
* Psychobilly
* Punk rock
* Punta rock
* *****core
* Raga rock
* Rapcore
* Rap metal
* Rap rock
* Riot Grrrl
* Rock
* Rock and roll
* Rockabilly
* Rock en Español
* Rockoson
* Rocksteady
* Russian rock
* Sadcore
* Samba-rock
* Screamo
* Shoegazing
* Shock rock
* Ska punk
* Skate punk
* Skate rock
* Sludge metal
* Soft rock
* Southern rock
* Space rock
* Speed metal
* Stoner metal
* Stoner rock
* Street punk
* Sunshine pop
* Surf music
* Surf rock
* Swamp rock
* Symphonic metal
* Symphonic rock
* Synthpop
* Thrash metal
* Thrashcore
* Trip rock
* Twee pop
* Unblack metal
* Viking metal
* Viking rock
* Visual kei
* Wagnerian rock
* Wizard Rock
* Zeuhl