gringo (used as a noun or adjective)
The origin of the Spanish word is uncertain, although it is likely to have come from griego, the word for "Greek." As in English, in Spanish it has long been common to refer to an unintelligible language as Greek ("It's Greek to me," or "Habla en griego"). So over time, griego's apparent variant, gringo, came to refer to a foreign language and to foreigners in general. The first known written English use of the word was in 1849 by an explorer.
It has been said that gringo originated in Mexico during the Mexican-American war because Americans would sing the song "Green Grow the Lilies." As the word originated in Spain long before there was a Spanish-speaking Mexico, there is no truth to this urban legend. In fact, at one time, the word in Spain was often used to refer specifically to the Irish. And according to a 1787 dictionary, it often referred to someone who spoke Spanish poorly.
In both languages, gringa is used to refer to a female (or, in Spanish, as a feminine adjective). In Spanish, the term Gringolandia is sometimes used to refer to the United States. Gringolandia can also refer to the tourist zones of some Spanish-speaking countries, especially those areas where many Americans congregate.
In English, the term "gringo" is often used to refer to an American or British person visiting Spain or Latin America. In Spanish-speaking countries, its use is a bit more complex with its meaning, at least its emotional meaning, depending to a great extent on its context.
Probably more often than not, gringo is a term of contempt used to refer to foreigners, especially Americans and sometimes the British. However, it can also be used with foreign friends as a term of affection, and it is also used frequently in a neutral manner. One translation sometimes given for the term is "Yankee," a term which sometimes is neutral but also which can be used contemptuously (as in "Yankee, go home!").
While speaking with newfound friends in Latin America, I (an American) have both been called a gringo in a friendly way and also been told I wasn't a gringo, so the connotation of the word can vary with region and context.
According to the dictionary of the Real Academia Española, the word in general means a person who speaks a foreign language, especially English, and can also have various meanings in certain countries. For example, in Bolivia, Honduras, Nicaragua and Peru, it can be used to refer to any blonde, fair-skinned person. And the word is sometimes used to refer specifically to someone from Russia, or to an unintelligible language in general.