Rambo is the soldier played by Sylvester Stallone in several US films, starting with First Blood, then Rambo: First Blood Part II, and later sequels. On screen he is muscled, lonely, and very violent; he fights the people the films treat as America’s enemies, including communists in the Vietnam-war stories. In ordinary English, calling someone a Rambo (or saying they are being Rambo) means they treat fighting and force as the only way to settle a disagreement — one person against the world, guns and muscles first. It can sound admiring in an action-film way, or critical: “Don’t go all Rambo on us” means calm down; talking would be better. It is informal, a bit jokey, and it expects you to know the films. The name itself is an old family name of unknown origin. It can be dated to the 17th-century Swedish immigrant Peter Gunnarsson Rambo; folk legend ties it to the mountain Ramberget (“Raven’s Hill”) in Gothenburg. There is also an old farm named Rambo in Vestfold, Norway (written Rambøe in 1664), and the Old Norse form might have been *Hrafnabú, whose first part is hrafn, “raven.” For learners, the useful meaning is the film hero and the violence-first person we name after him — not the Swedish hill.