wig-wag
n.— «The banjo crossing signal, also called a wig-wag, was (and still might be in some places) a round target with a hole in the center that swung back and forth when activated. Looked somewhat like a banjo being swung back and forth by its neck.» —“Re: What’s a Banjo Eye?” Usenet: rec.railroad May 10, 1990. (source: Double-Tongued Dictionary)
Further reading
The new Downton Abbey movie is a luscious treat for fans of the public-television period piece, but how accurate is the script when it comes to the vocabulary of the early 20th century? It may be jarring to hear the word swag, but it was already at...
It’s hard to imagine now, but there was a time when people disagreed over the best word to use when answering the phone. Alexander Graham Bell suggested answering with ahoy! but Thomas Edison was partial to hello! A fascinating new book about...