I understand that the word basement means:

the part of a building that is wholly or partly below ground level


But I wonder what American English and British English call 'the first basement floor right below the first floor of a building' and 'the second basement floor beneath the first basement floor'.

Is it all right to call it 'basement one' and 'basement two' in both AmE and BrE?

The most common English translation for what the Chinese call this type of floor is underground floor, or first/second/third/etc. floor underground, as evidenced by this link: http://eng.ichacha.net/underground%20floor.html

Is this terminology also acceptable in colloquial AmE and BrE, or is it more technical in nature?

  • 1
    I don't believe there is a single universal term, but in the US I've often heard "sub-basement" and even "sub-sub-basement" used for floors -2 and below. Probably "the basement", "the first sub-basement", and "the second sub-basement" would be well-understood and not too awkward. The other option, if you need to do this a lot, is to establish a notation of -1 for the basement and -2, -3... for sub-basements. (Though that gets confusing since sometimes zero is used for the basement.)
    – Hot Licks
    Jul 16, 2016 at 12:22
  • 2
    The OP has given his "best guesses," thereby demonstrating "research" undertaken over two days. He's asking about multiple versions of a word in two "dialects" (American and British English,) What more can you close voters reasonably want? That he looks up every "permutation when more knowledgeable people have an answer at their fingertips?
    – Tom Au
    Jul 16, 2016 at 15:44
  • 2
    This question was maliciously edited into utter nonsense. I just now rolled it back.
    – ab2
    Jul 16, 2016 at 15:59
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    In the UK, I've seen 'Basement Level 1'; 'Basement Level 2'; etc.. OP really needs to clarify which country (US or UK or elsewhere) he is concerned with - because the UK & US count floor numbers differently from one another.
    – TrevorD
    Jul 16, 2016 at 17:30
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    @HotLicks If 'zero' were used at all, in the UK it would refer to 'Ground Floor' (usually indicated by "G"): your first & second floors are our ground & first floors, respectively.
    – TrevorD
    Jul 16, 2016 at 17:50

3 Answers 3


The answer to a "proper" expression for underground floors is that there is no standardized nomenclature, rather, there are multiple different designators depending on the place in question and the country: https://en.wikipedia.org/wiki/Storey#Subterranean_floors

The numbering of levels below ground is also quite varied, even within the same country. In English-speaking countries, the first level below ground may be labelled B for "Basement", LL for "Lower Level" or "Lower Lobby", C for "Cellar" or, in the case of the Andy Warhol Museum in Pittsburgh, U for "Underground". In British buildings, LG for "Lower Ground" is commonly encountered (or lower ground floor).

If there is more than one basement, the next level down may be marked SB for "Sub-Basement". The lower levels may also be numbered B1, B2, B3, B4, B5, B6, B7, B8, B9, B10, etc.. Negative numbers are sometimes used: −1 for the first level below ground, −2 for the second one, −3, −4, −5, −6, −7, −8, −9, −10, etc. Lettered levels are also sometimes used: A, B, C, D, E, F, G, H, I, J, etc.

In Hawaiian, these levels are numbered I1, I2, I3, and so on. The "I" stands for "Ilelo", meaning basement.

Of course, that's not to say that people won't understand you if you use first floor underground, but I think the reason this isn't widely used is because it's just a mouthful. Five syllables, versus the three syllables of basement 1, or first basement.

First floor underground has been used, though, and can be found in various engineering books, particularly in the English translation of Chinese manuals:

Code for Fire Protection Design of Buildings

"If they are arranged underground or semi-underground, they should be arranged on the first floor underground but shall not be arranged on the third floor underground or below."

The 2nd International Symposium on Rail Transit Comprehensive Development ...

"Commercial space is located on the podium and the first floor underground, while the commercial apartment is located in the high-rise building on the north side."

Advances in Civil Engineering and Building Materials

"The first floor underground chooses the zoning control combined with the light tube during the day and close corresponding area lights and it is open the evening. The second floor underground is also lighting for garage."

Rainbow Town

"These two were the ones who said they wanted to stay on the first floor underground"

Civil Engineering in Japan, Volumes 6-8

"View of the illumination towers from the vicinity of the taxi station, the first floor underground."

CCDI Architecture: Interaction with a Complex Context

" The commercial building comprises the main department stores and retail business, with the supermarket and retail space on the first floor underground."

Re/collecting Early Asian America: Essays in Cultural History

"The first floor underground was the home of the "number two" employees. In the Chinese social code actors belonged in the lower strata."

...and more can be found in Google Books

Ngrams shows that basement floor is the outright winner compared to underground floor/floor underground/basement level/floor basement/lower ground floor/lower lobby/lower level floor/lower floor level/sub-basement/subbasement/sub basement. I didn't include lower level because the results would be corrupted by the common definition of level.

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If you're talking about a dwelling-house, then I would call the eerie floor under your groundfloor (where the spiders reside) your cellar. If you've turned it into a nice, cosy place to sit in at times, it's the basement. It's the same with your top floor. The attic is where those creepy creatures crawl, but if you keep it neat and tidy you could call it the loft.

  • Interesting commentary, but the question seems to be focused on the situation where there are multiple underground levels.  Also, do you have a reference for the above, or are you just speaking from personal knowledge? … … … … … … … … … … … … … … … … … … Please do not respond in comments; edit your answer to make it clearer and more complete. Nov 18, 2019 at 1:02

The floor below the ground is the basement, the floor below the basement is the sub basement, and the floor below the sub basement is a hypobasement.

  • You might want to include some source references to support your answer. Nov 17, 2019 at 20:46
  • 1
    I have never in my 70 years heard "hypobasement".
    – Hot Licks
    Nov 17, 2019 at 21:56

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