it will be bitcoin only as it is similar to any other currency. Bitcoin as like other currency is a collective noun.

example: we call 1 $ as a dollar and call 10$ as 10 dollar not 10 dollars.

... depends on the context, I would think...

It is my understanding that you would say "gimme 10 dollars" or "I owe him 10 dollars" or "this item costs 10 dollars"... but that you have to say "a 10 dollar banknote" or "a 10 dollar amount is what he got out of it" or "I'm browsing for a 10 dollar item".

source: Internet

Yeah if you hold more then one coin then you need to add that extra 's' to it and that would be the correct term to define 10 bitcoin's'.

Maybe we can standardize the way bitcoin balances are expressed. For me, I will use 10 BTC, 10mBTC or 10 bits, and not 10 bitcoin(s) etc.

Are we still using 10 United States Dollar(s) or 10 Great British Pound(s)? Most of us are using 10 USD or 10 GBP...

my mother language is PASHTO. our national language is URDU and optional language is urdu. we have a lot of grematical mistake. i cannot say any think about this. i usually use 10 bitcoins.

I used to say Bitcoin as well and always thought Bitcoins sounded somewhat a little weird but these days Bitcoins is used in the news and in the majority of articles. I tried it a few times and wrote Bitcoins instead of Bitcoin and it actually doesn't feel so bad and I've been using it more and more

Agree with that. If you are referring to more than one person, thing, place or idea, you need to add "s" most of the time. That's what I know too, 10 bitcoins is correct, just like 10 US dollars.

Not some, most of the currencies are described in the same way as you told above. Like Indian currency is Rupee and it's smaller unit is paise. Paise are always paise no matter what the amount is but Rupee is used as both 1 Rupee and 100 Rupees.

I think the plural is not really helpful as it is for fiat currencies. Unlike fiat, BTC is infinitely (well, to 8 d.p. in Core's current implementation, but I believe this is alterable) divisible, and thus when quoting decimal places it might feel nicer to use the singular form.

Other things to consider are that traders in Forex probably discuss exchanging "the Euro" and "the Dollar" against one another, for example, or say "I traded 5.30 Euro for ...", so we would like to streamline with that as far as possible. Also, the use of the plural is a subtle implication that bitcoin is held and bought or sold in whole units, which we all know to be incorrect, but those who are disinterested in bitcoin are often blissfully unaware of its divisibility, and to use the plural simply reinforces these erroneous beliefs. I think the singular makes it appear more fluid, which is one of its charms, and we should uphold that.