If someone is gung-ho, they are very, very eager — so eager that they may rush in, take risks, or even look ready for a fight. The sense you meet in action stories is this slightly dangerous heat: a gung-ho soldier who cannot wait to go in. Though actually, in everyday talk people also use it more loosely for anyone who is wildly enthusiastic about a plan, a job, or a team, with no guns in sight: “She’s gung-ho about the new project.” It can be a compliment (energy, courage) or a warning (too keen, not thinking). Informal. The word came into American English from Chinese 工合 (gōng hé), “work together,” which US Marines in China during the Second World War took up as a slogan; English then bent the meaning from “let’s pull together” toward “let’s go all out.” It is not from gun, and it is not from gungy.