(n.) an eroded meteorite impact crater
Those enormous rocky scars and hollows caused by meteorites crashing into the surface of the Earth are called astroblemes—a word that, rather pleasingly, literally means ‘star-wound’.
But in the sense of a wound or scar, is it safe to assume that the ‘blem’ in astrobleme is the same as in the word blemish? Well, as is often the case with jumped conclusions in etymology, nope, it is not.
The final –bleme of astrobleme doesn’t refer to the mark left by a meteorite so much as it does the actual hurtling of a rock into the Earth. Etymologically, it comes from the Greek verb ballein, meaning to throw or project something through the air. That’s the same root we find in ballistics, for example, as well as a few more recherché words like arbalest (a type of crossbow), and discobolus (a discus-thrower).
Somewhat confusingly, this root is also the origin of ball, meaning a dancing party (in the sense of dancers ‘throwing’ their bodies around), but not ball, meaning a circular projectile (which comes from an entirely unrelated root more closely linked to words like bale, balloon, and boulder). Even more confusingly, that males astrobleme a fairly distant etymological cousin of the likes of ballad and ballet, both of which ultimately derive from similar the same body-throwing roots as ball.
So where does that leave blemish? Well, it’s roots lie in another etymological and geographical direction entirely.
While astrobleme takes us back to Ancient Greece, blemish takes us back to the ancient Germanic languages of northern Europe. They likely shared a common root—equivalent to something like blas or bles—that was used to mean to injure or, more specifically, to discolour through injury. And it’s from there (probably via French, and the Frankish Germanic language in particular) that English picked up the word blemish sometime around the mid 1300s.