# What's the term for the inner perimeter of something?

Say I have a building with a sidewalk on its outside. To walk it I might say something like:

"I'm going to walk the perimeter of the building."

Now say I want to walk around the perimeter of the building again, but this time I'll be inside the building. How would I express the notion of "inner perimeter" succinctly? Is there a single word to describe it?

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Isn't "inner perimeter" sufficiently succinct? – Peter Shor Aug 13 '11 at 4:19

Since you are inside a room, the normal word to describe this would be simply "perimeter":

I'm going to walk around the perimeter of the room.

Or, for another common form:

I'm going to walk the perimeter of the room.

However, using the term perimeter with building always means the outside perimeter, so to refer to the inner perimeter, one must either say "inner perimeter", or use the word "room".

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Could someone (preferably the downvoter) explain what is wrong with this answer, so I can improve it? Thanks! – Daniel Aug 12 '11 at 20:20
(it wasn't me) All I can think is the switch to room rather than building. As implied in my own answer, I think the question is a bit odd anyway. If you're outside (a building) then so is the perimeter. If you're inside there are probably multiple rooms anyway, so the only "walkable" perimeter is still outside. And by any sane definition, the perimeter of a room is on the inside. Perhaps OP downvoted you because your answer makes it even more obvious the question itself is fundamentally flawed. – FumbleFingers Aug 12 '11 at 20:37
Have an upvote just so we can be back on level pegging at nil-nil! :) – FumbleFingers Aug 12 '11 at 20:49

This question presupposes a false distinction.

If the perimeter was a line drawn on a flat surface (cricket pitch, for example), a pedant might say you could only walk round it if every footstep fell directly on the line.

If the perimeter was, say, a line of close-set spikes sticking three inches out of the ground so you couldn't actually walk exactly on them, "walking the perimeter" would apply equally to just inside or just outside the line (or indeed randomly crossing over the line sometimes, thus including both).

It just so happens you can't normally walk the inner perimeter of a building, because there are usually dividing walls in the way. So by default it's assumed you mean the outer perimeter. If it is physically possible, and you want to say you're going to walk the inner perimeter, just say that. There is no more succinct way to express the difference.

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I disagree with virtually every statement here save the last. It's perfectly reasonable to want to, and need to express walking the inner and outer perimeter of a building or other construction. That's how you would inspect it for leaking and other problems. The inner dividing walls might make it harder, but none the less, the goal would be to inspect the interior portion of the outer most wall. – Hack Saw Aug 13 '11 at 3:09
@Hack Saw - there is no inner or outer perimeter as such - only a perimeter, which you may be inside of, outside of, or directly on. I couldn't agree more with FF. The fact the perimeter (in this case a wall) has depth, doesn't matter. – CJM Aug 13 '11 at 9:41
@CJM: Really? So if I ask an employee to inspect the perimeter, and they don't notice the mouse droppings because they decided to have a nice walk outside, everything will be okay with you, because they walked the perimeter as far as you are concerned? Meanwhile, an interior designer is going to care very much how thick the walls are, because the area described by the inner perimeter is not the same as that described by the outer. – Hack Saw Aug 14 '11 at 7:49
@Hack Saw: If you're lucky your employee will be smart enough to ask what you mean by perimeter. If you're not, I suggest it would be your fault for not being specific. By default the perimeter of any building is round the outside, obviously. – FumbleFingers Aug 15 '11 at 1:09
@Hack Saw: If you want to use 'perimeter' to approximate to 'inner perimeter' or 'outer perimeter', that is up to you. There is every chance that the listener might make the correct assumption, but equally, if you want to be sure, be precise. – CJM Aug 22 '11 at 19:59

I don't think you can do better than `inner perimeter`. If you have a sense of humor, you can use `E-ring` -- the Pentagon's inner perimeter ring.

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If you are speaking humorously, you might say, "Now I'm going to walk the battlements."

Better than that I cannot do, because I know a perimeter is, geometrically, a line of zero width, on which nobody can walk, so no sensible person (whether a pedant or not) would ever talk about walking a perimeter. Perhaps they would talk of perimeter patrols.

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If now you're walking inside and want to succinctly say that you are making your way through the building, visiting certain rooms and ending up in the same place as you started, you could say:

I'm going to make my rounds through the building.

The idiomatic phrase make rounds calls to mind a doctor going through the hospital and visiting each patient. The definition for the phrase says it means

to visit or call certain people or places

So if your trek through the building involves specific stops, this phrase would capture that meaning.

Another option is that you are taking a tour of the building. This term does not only imply that one is a tourist in a vacation locale -- the definition includes:

a journey for business, pleasure, or education often involving a series of stops and ending at the starting point; also : something resembling such a tour

So you could say,

I'm going to tour the building.

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Perhaps `perimeter` is not the word that should be in question. Instead, there may be a better word for `walk`.

For example,

"I'm going to pace the perimeter of the building."

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-1: You're right in that it does not solve the problem. – Daniel Aug 12 '11 at 19:14