Gung-ho

Gung-ho \GUHNG-HO\ , adjective;
1. Wholeheartedly enthusiastic and loyal; eager; zealous
2. In a successful manner

This word dates to 1942 and originated as a slang motto of Carlson's Raiders, a U.S. guerrilla unit operating in the Pacific in WWII. They borrowed it from Chinese kung hou* meaning "work together, cooperate". It was widely adopted in American English around 1959.

*So I've been looking around for this kung ho(u) word in all my Chinese reference sources and I cannot find it. Chinese is a difficult language and 'romanizing' the words (spelling them with letters we are used to) was highly variable until the mid-1950's, so it's difficult to pin down what this would translate to in modern pinyin. Additionally, this word was adopted by GI's with different linguistic backgrounds (i.e. accents) so the way it was understood and repeated would have been highly variable. Plus, there are accents and dialects in Chinese that would have made the word sound slightly different coming from different people (for example, nar in northern China is the same word as na li in southern China, just with different accents). Consider the English word car and the way it sounds when spoken by a person from Boston versus a person from Chicago versus a person from New Orleans. Now imagine a person from northern China hearing one of those versions and trying to repeat it to a person from southern China. See how muddled this can get?

Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Wednesday, January 26
Etymologies come from the Oxford English Dictionary and/or Etymonline.com