Southern Rock overlaps with that broad strip of Seventies blues-tinged rock called boogie, which ranges from ZZ Top to Brit combos such as Humble Pie who toiled on the US arena circuit and became vastly more popular in America than in their homeland. Boogie has a technical definition: a musician friend explains that it has to do with 4/4 being subdivided by 12 rather than 16 notes, with syncopations on the third subdivision of each beat. But the best way of conveying it is to just point at examples: "Get It On" by T.Rex (Bolan's 1972 T.Rextasy-exploitation flick was titled Born To Boogie), "Slow Ride" by Foghat, "Whatever You Want" by those dependable boys in blue denim Status Quo (who then got parodied by Alberto Y Lost Trios Paranoias on "Heads Down No Nonsense Mindless Boogie").
"Boogie" originally comes from "boogie-woogie", a piano-oriented style of blues designed for dancing, which emerged in the 1930s and filtered into numerous corners of American popular and roots music.
A strange, mobile word indeed to be appearing in all these different contexts: