Last weekend I went to Austin to see my sister graduate from the University of Texas (congratulations, Ellen!). During the visit with Mom, Dad, Glen, and Ellen, we had several conversations about English grammar, and just before they took me to the airport for my return flight, Dad was complaining about the strange vocabulary used by airline employees. Now for years, he's expressed his dislike of the word deplane, meaning "to disembark." ("To deplane should mean to remove planes from someone!") This time, though, he had an item that was new to me: the use of ramp to refer to what the rest of us call the runway or the tarmac. He said people in the industry could be quite adamant about using this term, and that he had even had a heated discussion on the subject with my uncle, who is a commercial pilot. My uncle's position: It's not made of tarmac! Dad's position: Even so, it's not a ramp!
I think calling a runway a ramp is just plain wrong, too, but my family expects me to put on my descriptive hat in situations like these, so I did.
"Well, Dad, I'm sure you wouldn't object if I told you that ramp can also mean a kind of wild leek found in Appalachia, would you?"
He said no. So he wasn't in principle against ramp being an ambiguous word. He (and I) could accept both the "inclined plane" and "wild leek" meaning for ramp, but not the "runway" meaning. Why not?
"So," I said, "when someone uses ramp to mean 'wild leek,' you accept that they have two meanings for the word. When they use it to mean 'runway,' which is hard and flat like a ramp, but doesn't have the one essential property of being an inclined plane, is the problem that it looks like they think they're dealing with a single concept, and they're not?"
"Yeah!" said Dad. "Exactly!" added Glen.
It made sense to me, too, but I wonder: How much in common with an inclined-plane-type ramp does any given object have to have before calling it a ramp triggers alarm bells for people like Dad and Glen and me? Is being human-made enough? What if a certain kitchen utensil were called a ramp? I think I'd be OK with it. Maybe human-made plus flatness is enough. Could a kind of bed be called a ramp? No, if I heard of a bed called a ramp, I'd wonder how you'd keep from sliding out of it. What about flatness all by itself? Could a plateau be called a ramp? No, I'd object to that in the same way as I do to calling a runway a ramp. Is having an incline sufficient? Could a soft, squishy slope of mud after a mudslide be called a ramp? I'd say no, since you can't move stuff up it; evidently, the function of helping move things is an essential part of the definition of ramp. I know plenty has been written on the question of "how alike do X and Y have to be before they can be denoted by the same word?" (for example, see this page about Eleanor Rosch, as well as all the current IT work on ontologies), but this question of "how alike do X and Y have to be before the differences between them preclude giving them the same name?" is one I haven't run into before.