Sorry to disappoint the more salacious-minded of you, but this post will not be providing images of women's upper thighs bedecked with lacy undergarments.
We will in fact be dwelling on titillating images like this one:
and asking the question, "Why are they called garter snakes?"
For they are indeed "garter snakes", not "garden snakes" as their name is often corrupted. This corruption (I use this word in its dispassionate linguistic sense of "change from the original") is a result of folk etymology -- because they do indeed turn up in gardens -- reinforced by the North American phonetic tendency which makes us pronounce "garter" as "garder". Be that as it may, "garter snake" is the correct term.
It is perhaps not surprising that people associate snakes more with gardens than with garters, because our mental concept of what a garter is has changed quite a bit since this family of non-venomous North American snakes acquired its name in the 1700s. Back then, garters did not look like this (that would be a pretty bizarre snake):
but often more like the two garters (one 16th-century Italian, the other 18th-century American) at the top of this post. They had evolved from the basic woven garters of the Middle Ages, which probably looked something like this:
You can immediately see why a European coming on a snake like this in his North American travels, and just possibly fantasizing about undergarments at the time, would be inspired to call it a "garter snake". The one below looks particularly as if someone had woven it a nice garter-like suit.
The word "garter" came into English, like many garment-related words (including "garment" itself) from French after the Norman Conquest. In Old French the garet (modern French jarret) was the back of the knee (something for which we don't have a word in English). This was where garters were usually fastened. The word ultimately derives from the word for "leg" in the Celtic language of the pre-Roman inhabitants of Gaul.
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