Preface ADDED 14
Jan/Jan 14, 00:11
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This answer, as the OP Lucian Sava is well aware, has been written from an AmE perspective.
Actually, it is written from the perspective of the variety of AmE that I speak.
I think Lucian gets by now that English usage is not universal, as I had already indicted in my anwer.
Let the conversation continue, by all means!
Serpentine is fine, but in English I am pretty sure we would use it as an adjective describing the road.
Such a road is also called, in familiar terms, a curvy mountain road.
More technically, it is any road that contains many switchbacks or hairpin curves Switchback can refer to entirety of such a road.
But this may not reflect universal usage.
I think serpentine (adjective) would be the more universally recognized word.
You can do an image search for both "switchback road" and "serpentine road" and get many of the same images.
Thus saith the snake:
ell.stackexchange.com/users/None/
Suitable words might be: winding or twisting
You could check the Thesaurus for more options.
These are very general adjectives and don't just apply to mountain passes (a pass is a road that crosses a mountain, but it does not have to be winding).
Note that there is a pass over the Pennines called Snake Pass , but that is its name.
You could use Serpentine but that is rather poetic sounding.
The type of turn that loops back on itself is known as a hairpin turn .
ell.stackexchange.com/users/15464/rghome
In the U.S., we call those mountainous roads "switchback" roads, with the individual turns called "hairpin" turns. https://www.google.com/search?q=switchback+road&espv=2&biw=1147&bih=685&tbm=isch&tbo=u&source=univ&sa=X&ei=qUy0VKO3KtWxogSMpYDIBw&ved=0CB0QsAQ&dpr=0.9
ell.stackexchange.com/users/15493/Lance Ike
I often refer such paths/roads as .. zig zag roads or paths Searching this on Google Images supports this word.
In my state, we have such place called Saputara .
It's famous for its hairpin curves or zigzag roads.
Most of the tourists experience motion sickness due to this.
ell.stackexchange.com/users/3187/Maulik V
I think serpentine road or winding road is as close as you're likely to get.
Personally, I prefer serpentine road .
To my knowledge there isn't a single-word noun form of this phrase that is generally understood.
Another user mentioned switchback , but that strikes me as less likely to be widely understood.
ell.stackexchange.com/users/15496/Paul Senzee
In england we do not speak of serpentine roads and a swichback (n) is not a road and a switchback (adj) road is not a bendy one.
We are notorious for winding roads but these are not necessarily winding to ascend a hill or mountain.
Meandering is more often applied to a river than a road and would not describe a bendy climbing road.
We speak of hairpin BENDS rather than curves or corners.
I do not think there is in British English a particular noun or adjective pertaining particularly to roads made with bends to reduce the gradient on a hill.
This may be due to lack of mountains and hence such roads in england; there may be Welsh or Scottish words for such.
ell.stackexchange.com/users/15525/user15525
Instead of a 'road' you could instead call it a 'track.'
'Track' refers to it being a dirt, rather than sealed, road.
So 'winding track' rather than 'winding road,' for example. http://dictionary.cambridge.org/dictionary/british/track
ell.stackexchange.com/users/2598/Tamsyn Michael
This would be a road containing many s-bends or hair-pin corners.
ell.stackexchange.com/users/15478/Tom Bandy
The word that you are looking for is " meandering ".
ell.stackexchange.com/users/15484/GatesReign
It is called a mountain pass .
You can definitely use words like "serpentine", "sinuous", "winding" and so on to describe such a road but they're just appropriate adjectives.
To give an analogy, answering the question "What is this type of road called?"
with "a serpentine road" is a bit like answering "What is this this type of animal called?"
with "a huge animal" rather than "an elephant".
ell.stackexchange.com/users/4468/David Richerby
I’m looking for a word or a phrase for describing this kind of  road  which usually is constructed in the mountain areas, but not only:   image a representative sample from Google images, query = transfagarasan  In my language we call this  serpentine  a word used as a noun (not adjective) to describe its shape.  If I wanted to write an article about this road, a road constructed in the mountains provided with many turns and angles like in the above link, which word would be more appropriate to use?
What is this type of road called in English?
ell.stackexchange.com
<word-request><phrase-request>
ell.stackexchange.com/questions/46490
ell.stackexchange.com/users/3223/Lucian Sava
Suitable adjectives would include meandering, serpentine, sinuous, winding, twisting, zig-zag. However, serpentine would be the more universally recognized word. Meandering, serpentine, zig zag, twisting, winding are all options.
Meandering, serpentine, zig zag, twisting, winding are all options.