Arch - ∩ or U?

[volt]

As a noun, does 'arch' usually mean the shape like a bridge, i.e., curved with middle section higher, two ends lower (like ∩)? If it is the same curve but middle section lower, two ends higher (like a U), is it still called 'arch', or 'reversed arch'?

As a verb, when you read "to arch" something, should it be taken to mean to shape like a bridge like ∩, or could it also be understood as possibly U shaped? (In other words, if the author means to say to shape something like a U, should he qualify it with the word "reverse(d)" or not?

 

[Riverby]

Interesting question. My view is:
1. If you are talking about architectural features, use arch only for this shape: ∩.
2. If talking about people, an arched back is bent backwards. That is, the navel sticks out in front.
3. If talking about cats, the arching is opposite to that of people. That is, if the cat is standing on its four legs, its back is this shape:∩.

 

[ewie]

∩ ~ I'd call that an arch.
U ~ I'd call that a U [letter U]. I suppose I might call it a reversed arch or an upside-down arch if I was talking about an actual physical architectural feature, yes. But if I was just talking generally about the shape, it'd be U or U-shape.

 

[Gwan]

2. If talking about people, an arched back is bent backwards. That is, the navel sticks out in front.
3. If talking about cats, the arching is opposite to that of people. That is, if the cat is standing on its four legs, its back is this shape:∩.

Hmm, I suppose you're right, although if someone were doing yoga I would picture the cat-version as the arch and the reverse of that as... something else... Anyway, that's not of material importance but you got me thinking!

 

[volt]

Thanks for the replies!

Interesting question. My view is:
1. If you are talking about architectural features, use arch only for this shape: ∩.
2. If talking about people, an arched back is bent backwards. That is, the navel sticks out in front.
3. If talking about cats, the arching is opposite to that of people. That is, if the cat is standing on its four legs, its back is this shape:∩.

Very interesting distinctions! Especially interesting humans and cats are treated differently (why is that, though?). Now, what about when you talk about a person (not cat) lying on his back horizontally, what makes an 'arched back'? What if he's lying on his stomach--will it make difference?

 

[Riverby]

I don't know the answers to your questions. But try putting "arched back" into a search engine, using the images option. That's what I did for my earlier reply (#2).

 

[brian]

For me it's all about the perspective of the observer - which of course is normally from the ground, as we're all used to. Whether a person is lying belly- or back-down, if that person "arches up" or makes an "arch," it simply means they keep their toes and hands on the ground and make a ∩ shape. In one case, the belly button and pelvis will be raised (like in gymnastics), in the other case the back and buttocks (like kids who line up and make tunnels for other kids to crawl under, or non-athletes trying to do push-ups ).

Even in the case of a cat, if the cat were to get scared or stretch, where the middle of the spine raises really high and its fur sort of frizzes out, I'd call that an arch - perhaps, "The cat arched up sharply" or "...made a sharp arch" or something.

So in other words, so long as from my perspective (or from normal, ground perspective) the shape is ∩, it's an arch.

 

[Sikaranista]

"Reversed arch" sounds odd to me.

The closest term I can think of is "concave"

http://www.merriam-webster.com/dictionary/concave

The oppositve of concave is convex, which is from a Latin term meaning arched or vaulted

http://www.merriam-webster.com/dictionary/convex