Threshold.

In houses with mud floors, the stalks of wheat (thresh) were spread about as a kind of insulator and absorbative. A thresh hold was a block of wood at the entrance which stopped the thresh from getting spread through the doorway.

This grew to mean the boundary between the house and the rest of the world, to the point of symbolic ownership. When you cross a threshold you are going from one domain to another.

We now use it to mean a limit, or the how far you have to go before something changes or breaks. Kinda cool.

The other one is arrowhead. Terry Pratchett wrote a great piece on “ontic dumping”, where we use one word to mean one thing then associate it with another thing and the connection is just automatically known by all.

So ->

We know what this means right. Go in this direction, look at this direction, the thing which needs attention is in this direction. There are arrow heads everywhere. On signage, on interfaces, even on the spacecraft which we have sent careening off into the universe. If other species are out there, they might interact with an object which had an arrowhead on it and would have absolutely no concept of what it means.

Why does an arrow have a head anyway? Because that’s the way an arrow flies right. The pointy bit, which we call the arrowhead, moves in the direction that it’s pointing. Which is bullshit, because if you hold an arrow horizontally then drop it, it goes straight down. And it only flies in that direction if you apply force at one end of the arrow and propel it in that direction.

But WHY IS IT CALLED A HEAD?

It doesn’t resemble a head. There’s no body. Heads don’t usually “point” in the direction of travel. Yet we have taken a word that means “the bit that is important”, because we’ve determined that a head is an important thing, and the bit of a thing whxih does the most of the thinging should be called a head.

It baffles me.