laser
I recently saw the word laser in a premodern context where it clearly wasn’t referring to Light Amplification by Stimulated Emission of Radiation. Which confused me.
Turns out that laser is also a name for a plant called silphium, and for the resin of that plant.
Silphium is itself a little mysterious: “It was an essential item of trade from the ancient North African city of Cyrene, and was so critical to the Cyrenian economy that most of their coins bore an image of the plant. [But the] exact identity of silphium is unclear.”