ETYMOLOGY 101
The origin of: eavesdropper
I’ve decided to stop doing a word history of one of the “3 words” listed on the first page, since it limits my ability to talk about far more interesting and commonly used terms. So, ever wanted to know why we call people who listen surreptitiously to the conversations of others eavesdroppers?
               The verb eavesdrop as we use it today first appeared in the 15th century, and was a descendant of the Middle English noun evesdrop and evesdrip. In the 9th century, these words referred to the water that falls in drops or drips from the eaves of a house. The term later applied to the area on the ground under the eaves where this water fell. Thus, one who stands within this area (known as the eavesdrop) is known as an eavesdropper. Since the eaves of a house typically don’t extend far from the house, when one stands under them it is easy to hear what is going on inside.

The origin of: hamburger
Why do we call ground beef patties hamburgers? The name has nothing to do with the meat used, but with the origin of the meat. Hamburgers were first cooked up in the German city of Hamburg, were the ground beef was known as “Hamburg Steak.” German immigrants brought the name and the steak to America in the 1850s, where it was subsequently transformed to hamburger steak. By 1908, the meat was known simply as hamburger.
               The Germans also introduced two other popular types of meat to our diet and our language: frankfurter comes from the city of Frankfurt, and is commonly shortened to frank. Similarly, wienerwurst, or wiener, comes from Wien, the German name for the city of Vienna.
               Wurst is German for “sausage.” Schnitzel in German is literally “shred” or “shaving.” Brat is German for “meat without waste” (no, bratwurst does not come from Brat, but from Thuringia, a state in Germany).

The origin of: taxi
Why do we call those ubiquitous yellow cars thus? The word comes from the mechanical devices that are installed in taxis to calculate the distance traveled and the fare due the driver. The device was called a taxameter by the Germans (from the Latin tax for a tax or charge, and the Greek meter for “a measuring device”), and a taximetre by the French. Cabs that used this mechanical device were called taximeter cabs. This was eventually shortened to the present taxi.
               Cab is a shortened form of “cabriolet,” a two-wheeled, horse-drawn carriage popular in France and Italy in the 19th century. Today the word refers to any car body style that has a retracting rooftop.

Source: The Merriam-Webster New Book of Word Histories.