The Tricky Art of Definition

[Swatopluk]

To define anything is an art by itself. Most short definitions used are either too exclusive or inclusive or even both.

Bird: flying animal
  Snakes on a plane
flying without human help
  tortoise carried away by eagle
flying without help from another living entity
  "paragliding" spiders
flying with only their body
  flying squirrels
that's gliding, flying with wings
  dragonflies
vertebrate winged animal flying using its own power
  flying fish
gliding again and not warmblooded
  bats
Aaargh! egg-laying warmblooded vertebrate winged animal flying using its own power
  pterosaurs
Tricky, hm, not extinct
  harpagornis
drat, that's a bird but it's indeed extinct. OK, strike the extinct and add feathers
  some pterosaurs might have had feathers
OK, you get me there. Anything else?
  ostrich, dodo, moa, penguins, all flightless. not to forget Galapagos cormorants
Aaaaaargh! I give up
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You see the pattern, I presume

OK, now the game: Take a common word and give a short, concise definition. then let the rest try to poke holes in it.
Condition: No explaining pictures in the definition, only for hole-poking.

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How would you define spiral staircase?

[Pachyderm]

Spiral Staircase:

Vertical yet rotationally lateral duo-directional access assembly

[Swatopluk]

Does it have to be strictly vertical?
Are there no simpler words that everyone can understand ?
I'd say for the sake of definition "stairs" is well-defined enough, so it would be sufficient to explain how the spiral staircase deviates from the "normal".
Most staircases are "rotational" in a way though not usually circular.*
I thought about a potential design for a moving spiral staircase. that would remove the bi-directional.
Open to discussion: does a stair that goes only half a circle round** already as spiral stair case or is a full 360° turn necessary (what about 359° )?

*
**

[Griffin NoName]

That last is merely curved. Perhaps it has to appear to complete a full turn (359/360).

Coonsider the double helix at Chateau de Chambord. It boggled my mind when I visited the Chateau.

[Swatopluk]

Personally I think anything beyond 180° could apply for spiral staircase status, if it is tightly wound (no free space in the center).
Btw, the second picture was chosen for lack of a better one.

I have to admit that I have trouble to come with up a waterproof definition even in German.
In order not to exclude some possible but weird constructions (e.g. a central axis that is itself a curve) would require some heavy mathematics in the definition stating that to be included it has to be transformable into a basic form* using only certain operations that do not change the main topology.

*like
x=r*sin(phi)
y=r*cos(phi)
z=a* phi
describing the main direction curve of the staircase

There are some architects that would build 7-dimensional staircases, if the budget allowed it

The typical spiral staircase does not contain any spiral though those in domes occasionally do (getting narrower towards the top).
the German "Wendeltreppe" is a bit more precise on that. "Screw Staircase" was probably rejected by the prude committee .

[The Meromorph]

A 'spiral' staircase does not contain any freespace in the center, but does have a central support element. Any staircase containing free space at the center is a 'circular' staircase (even if it's not circular e.g. square).

[Swatopluk]

I know some staircases where that distinction would be tricky too.
I just checked the German wikipedia and found that there is even an extra disctinction between Wendeltreppe and Spindeltreppe, the latter having a straight upright pillar in the center, while with the former any inner side (real or theoretical) is also winding helically.

[Sibling Lambicus the Toluous]

Spiral Staircase:

Vertical yet rotationally lateral duo-directional access assembly

You know, I have a vertical yet rotationally lateral duo-directional assembly in my kitchen drawer that I use to access the contents of wine bottles.   

[Griffin NoName]

Spiral Staircase:

Vertical yet rotationally lateral duo-directional access assembly

You know, I have a vertical yet rotationally lateral duo-directional assembly in my kitchen drawer that I use to access the contents of wine bottles.   

May still be valid.... I bet you climb the walls when you can't find it

[Swatopluk]

Well, I'll be screwed (unfortunately not in the sense now associated with it).

Hm, does anybody remember that scene in The Lavender Hill Mob where Guiness and Holloway run down the stairs of the Eiffel Tower and get slightly disoriented as a result ?

[goat starer]

i define a spiral staircase as "a staircase of spiral form"

Also i NEVER (except immediately above) define a spiral staircase in the absence of one - in their presence I tend to use the definition....

"look at that bloody great spiral staircase"

or similar

[Swatopluk]

Except that a spiral staircase is typically spiral free. A spiral is a curve with increasing radius, while the standard spiral staircase has a constant one (which again differs from a serpentine that moves at right angles to its main directions).
Or in other words, the term spiral staircase is quite misleading.

That  is not meant as being condescending towards our treasured revolutionary goat.

Btw, your post reminds me of something out of the third book of Gulliver's travels where the author proposes that people should not be allowed to talk about things not present. The implication is that people should carry big sacks wherein they store the items they expect to talk about .

[Griffin NoName]

Btw, your post reminds me of something out of the third book of Gulliver's travels where the author proposes that people should not be allowed to talk about things not present. The implication is that people should carry big sacks wherein they store the items they expect to talk about .

Sounds like Zork to me.

I know Goat is often sent into the desert carrying heavy loads, but it seems unreasonable to expect him to go around with a spiral staircase on his back.

[Swatopluk]

Let's start a debate whether models or depictions do fulfill the condition?
Btw, do you have a material depiction at hand, so I can use the word ?
A lump of plasticine should be sufficient for most purposes.
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What's the next word, doc?

[Swatopluk]

OK, here is a new list. Make your choice and define away

axe
bush, bed
chair
drop
eagle
fire
garden
hose
icon
juggler
kelp
left
monster
nose
orgasm, oven
power
question
rocket
sword
tower
umpire
vanity
water
xylophone
yoghurt
zither, zealot