Gung-ho is a phrase borrowed from Chinese, frequently used in English as an adjective meaning enthusiastic. The original Mandarin phrase is gōnghé (工合), a standard abbreviation for gōngyè hézuòshè (工業合作社), meaning industrial worker's cooperative. (It is true that gōng means work and hè means together, but gōnghè by itself is not a standard Chinese term and serves only as an abbreviation for the longer phrase: an English-language analogy would be "IndCoop".)

The phrase entered the American vernacular when it was picked up by then-Major Evans F. Carlson , USMC. According to Carlson, it was used as a slogan by the WW2-era Chinese Communist Party's 8th Route Army, led by Zhu De. However, Carlson's purpose was inspirational, not necessarily historical, and this claim may be inaccurate.

Carlson traveled with the 8th, and later used gung ho during his (unconventional) command of the 2nd Marine Raider Battalion. From there it spread throughout the Marine Corps (hence the association between the two) and into American society as a whole. It is now often used in the ironic sense of excessively enthusiastic, overzealous.