It's true that girls often call their close female friend(s) girlfriend(s) , at least in the US.
And although I am inclined to believe that the friend is likely a platonic female friend, it is still ambiguous.
girlfriend 1.
A female companion or friend with whom one has a sexual or romantic relationship.
2.
A female friend.
If you really care to know, you should ask her for clarification.
ell.stackexchange.com/users/36187/Em.
It depends where in the world you are.
Everywhere, as far as I know, one meaning of "girlfriend" is "a woman you're having a romantic and/or sexual relationship with but aren't married to."
In the US, it's very common for women to describe close female friends as "girlfriends", even when there is no romantic or sexual involvement.
In the UK, the friend-who-is-a-woman meaning
is much less common than in the US and would be seen as something of an Americanism.
Having said that, the proportion of women in the UK who use "girlfriend" to mean any close female friend could easily be higher than the proportion of lesbian and bisexual women.
If that's the case then a woman saying "my girlfriend" in the UK would still be more likely to mean "my close female friend" than "my romantic/sexual partner".
ell.stackexchange.com/users/4468/David Richerby
The other answers have done a great job, and I fully agree.
If a girl refers to another girl as a "girlfriend" it could mean either way
but it's very common to refer to just a female friend.
I wanted to add some additional information to say that this (for whatever reason) is very specific to one girl referring to another.
If a girl said "boyfriend" most people would would assume that means a romantic relationship, and it would sound weird otherwise.
I have heard "guy-friend" to refer to platonic male friends, but I'm not sure how common this is.
(It might be regional)
Similarly, if I (a male) were to refer to someone as a "(girl|boy) friend" most people would infer that I mean a romantic partner.
I probably would too.
I would never refer to a platonic friend as a "(girl|boy) friend", and it would sound very strange to hear someone doing so.
ell.stackexchange.com/users/15406/James
Unlike boys, girls very often call their close female friends girlfriends .
ell.stackexchange.com/users/43654/Gat
Even as a native speaker (a gay one, at that)
this can be ambiguous.
In my experience, using "girlfriend" to refer to friends is something that older women do and probably not the under-thirty set that is more used to gay culture.
However, I've always lived in liberal, very gay-friendly environments so I wouldn't be shocked if I found that young women in less LGBT-friendly American regions used "girlfriend" as a synonym for "friend".
If understanding were crucial to your conversation, I think asking "Is she just a friend or are you two dating?" would be perfectly acceptable.
ell.stackexchange.com/users/6308/thumbtackthief
Often, if the ladies in question are in a romantic relationship then they will refer to each other as their partner (this is true for both genders).
As mentioned, that doesn't also preclude them from referring to each other as girlfriend as well.
ell.stackexchange.com/users/43723/BanksySan
I have a classmate and sometimes she says something like "I told my girlfriend that she has to blah blah".  Does this wording imply a lesbian relationship, or is she referring to a her best friend (a girl) only?
When a girl mentions her girlfriend, does she mean it like lesbian girlfriend?
ell.stackexchange.com
<meaning><meaning-in-context><word-meaning>
ell.stackexchange.com/questions/107424
ell.stackexchange.com/users/40604/Ashkan Sirous
it's very common for women to describe close female friends as "girlfriends", even when there is no romantic or sexual involvement. However, if a girl refers to another girl as a "girlfriend" it could mean either way. It depends on where in the world the speaker is, because universally "girlfriend" implies a romantic relationship.  However, Especially in the US but also in other parts of the world, girls often call their close friends "girlfriend", although older women tend to use the word in this way more. Therefore, its usage is ambiguous. Since it is ambiguous, it is best to ask for a clarification. Also, bear in mind that when two girls are in a romantic relationship, they often refer ro each other as "partner"
Especially in the US but also in other parts of the world, girls often call their close friends "girlfriend", although older women tend to use the word in this way more. Therefore, its usage is ambiguous. It depends on where in the world the speaker is, because universally "girlfriend" implies a romantic relationship.  Since it is ambiguous, it is best to ask for a clarification. When two girls are in a romantic relationship, they often refer ro each other as "partner"