A sixth-grade teacher in San Antonio, Texas, is skeptical about a story that gringo derives from a song lyric. He’s right. The most likely source of this word is the Spanish word for “Greek,” griego, a term applied to foreigners much the same way that English speakers might say that an unintelligible language is Greek to me. The ancient Greeks, on the other hand, imitated the sound of foreigners with the word barbaroi, the source of our own word barbarian. This is part of a complete episode.