The word "haters"..

[CurlewKate]

...do you use it, and if you do, what do you mean by it? What context would you use it in?

It always sounds very childish to me.

Only if I were being deeply sarcastic and saying some variant on 'Haterz gonna hate', probably to a friend annoyed at a bad review of their new book from a reviewer who'd also disliked the last one.

It's not a word to be used seriously.

It has lost all meaning now. People just use it to pre-define anyone who disagrees with them as being on the wrong side of history.

Used to mean something but has gone to bollocks like most online discussion of issues seems to be doing