The Merriam-Webster Word of the Day for August 29th was defile. The surprise definition:
to march off in a line
Here is what M-W provided on this word:
The "defile" that means "to contaminate," a homograph of today's Word of the Day, dates back to the 14th century and is derived from the Old French verb "defouler," meaning "to trample on" or "mistreat." Today's word, on the other hand, arrived in English in the early 18th century. It is also from French, but is derived from the verb "défiler," formed by combining "de-" with "filer" ("to move in a column"). "Défiler" is also the source of the English noun "defile," which means "narrow passage or gorge."