Fluent.

Native means you grew up speaking it.

English is my second language and also my best language. I like to joke that "English isn't my first language" when I say something silly - always good for an eyeroll from my spouse. But generally, I consider English my best language and my first language as my first/native language, I guess.

It depends on whether you treat the answer as "like a native" or "I am a native". The word native is etymologically rooted in "born into it".

To sum up: You can speak a second language better than a native and have a proficiency of a native speaker without being a native speaker of the language.

My first language was Polish, but I've lived in the US most of my life and my English is better than many Americans'. So now I say that I'm a native English speaker who is fluent in Polish.

Native means you grew up with it. Otherwise it's not native no matter how good you are.

I think there's a difference between first language and native.

I believe native means a level of language equivalent to the people of the place where that language is talked.

A first language is usually spoken at native level because most people will have been using it all their lives. But if you don't because you moved away or whatever reason I don't think you'll have a native level.

On the other hand you can become native in a language that's not your first language. If you speak it so well that's indistinguishable from any other person from that place.

I just say my Spanish fluent. I can have a conversation, but it will have a lot of pauses as I try to remember a word. Certainly not usable at an academic level.

I was graced by parents who don't know their own language very well. Google Translate's more reliable, so there is a lot of vocabulary I don't know simply because it's never been brought up in my family.

I just consider English my main language. I feel bad for the immigrants who were raised not even knowing their language though. Met a few.

I speak four languages at native level, because I can change languages mid sentence and you wouldn't know which one is my actual origin language (hint: it's two).

I'm more than fluent. Fluent just means you can speak in complete coherent sentences without hesitation. You can do this but still have a strong accent - like many of the Indian tech wizards, for instance.

Native, to me, means that it's practically indistinguishable from a person that grew up in that country, and you can't tell that I didn't actually grow up in that country.

My first language is Cantonese, spoken by parent at home.

My second language is Mandarin. Only spoken in school when I was in China, which lasted till I was like grade 1-2.

My third language is English (USA English, that is). Started learning around grade 2-3.

Since arriving in the US, I basically never spoke Mandarin ever again. Like 10+ years now.

English is my most fluent language. I could probably form complex speeches in English, well I mean... I'm basically born here, minus the first decade of my life. I can maybe say a few basic ideas in Cantonese, but cannot discuss anything meaningful like politics, medical stuff, or bussiness terms. I can barely express any ideas in Mandarin. I'd have to think about it in Cantonese, then convert it in my mind into Mandarin, although both are Chinese, there are some unique "quirks" that make some phrases slightly different.

If I went to China today, I'd probably sound like either (1) a new immigrant from korea, japan, or vietnam; or (2) someone with an intellectual disability. In contrast, I could probably talk to any tourist or bussiness people visiting China and have a full conversation with them and they'd be shocked why a "Chinese looking" person can speak perfect English.

I have no idea what "native" language even means anymore. I'd probably describe English as my "most proficient language" and Cantonese as an "old and forgotten tongue"

Depends how badly you speak your native language?

Nah, I just judge the native speakers who suck at their own language (jk I'm not that much of a dickhead)

I call it my "main" or "primary" language. My first language lacks vocabulary due to atrophy and stopping learning it after turning 9.

I learnt german in school, and lost it all.

I'm currently learning spanish

From a linguistics standpoint, there are some things you have with a native language that you don't have with a second language by definition (e.g. native speaker intuition). By that metric, your second language cannot be native.

But it's actually more complicated than that. I'd suggest there needs to be better definition on what counts as a second language for your question.

Brain plasticity as it pertains to language acquisition may (=depending on what study you cite) stick around until the late teens. That means that consistent and continued exposure to a language community will ultimately lead to acquisition if the learner/acquirer is not beyond the critical period threshold. If that occurs, you'd be a native bilingual (or multilingual), and you wouldn't really have learned a "second language". You would have two native languages, and in both you would have e.g. native speaker intuition.

This is kind of what you're asking, but the issue is what is meant by "second language". If you mean an L2 which was learned by someone after the critical period, then I'd argue that speaker would never be native in that L2 regardless of their proficiency. But if you mean an L2 which was acquired before thr end of the critical period, then by definition it is another native language, not a second one.

I'm still better in my native tongue than in English, but I would still consider myself 'fluent', with some people considering me 'native', which I would never claim for me. This I would call "personal relativity", as I am probably more fluent in English than quite some native speakers. And I definitely read English faster than most native speakers.

I just describe it as "bilingual level", because fluent is often used but can represent a range of levels depending on how demanding you are.

For me, fluent is what I'd describe someone who's studied well and can live only speaking the target language. They may have a crappy accent, make mistakes but they know they can express their ideas and be understood and generally don't search for words.

I'd use "native level", but that can be a bit misleading too.

And so, that's why we have exams/diploma with levels and such.
If someone tells you they have a C2 level diploma in French, I assure you that their command of French is worthy of respect even for a native French person.

If I tell you I have HSK3/4 even in Chinese, you know I'm nowhere near fluency, despite how well I can fake it with what little I do know! :P