What exactly does toxic mean?
I don't think there's an exact definition, but here's my best approximation:
People who take more than they give.
Who are corrosive to your wellbeing, and unable or unwilling to change despite the harm they cause to those around them, even when this harm is pointed out to them.
The unpleasable, who only see their own needs and cannot empathise with others'.
People who cannot respect you as a sovereign human being in your own right, with your own thoughts, feelings and opinions, and instead seek to manipulate or control you, and are insensed by the existence of your own throughts, feelings and opionion when those come into conflicts with how they think you should be.
i don't like labelling people
Labelling people is not a good thing, I agree. But it can be a temporary help when you are struggling to understand why you get so upset at someone's behaviour: some find it helps "allow" them to start saying No to that behaviour, where before they may have endured that behaviour in silent discomfort. For example, even though only a MH professional can make a diagnosis, you might benefit from a feeling of "OMG, it's not me; it's them!" if you find your PILs in lists of common traits of the personality disordered. Plenty here have.
The label doesn't have to be a permanent thing, rather a help towards identifying those behaviours which you will and will not accept. As you are perfectly entitled to do. I mean, that's the ultimate aim: not to label others, but to be clear about where your limits lie, and to feel entitled to enforce them.
If you can do all this without any labels anywhere, more power to you!