Well, strictly speaking it is a feeling of detachment. It can have a lot of
different manifestations for different people.
For me, its the weird feeling (sometimes euphoric) I get when I am in
the middle of something, usually an important business meeting and
suddenly, like a hit to the back of the head, I realise I am in this room
talking with other people, and I dont quite feel myself. I sort of feel
like I am looking at myself in the third person.
For me its kind of a "high" feeling. Perhaps a slight realisation that I
am not as in control as I sometimes think I am.
When magnified, in situations of panic, or perhaps when highly
stimulated, I find it feels like a bit of an outer body experience. I know
its not, which is what differentiates it from a delusion or hallucination,
but it definitely feels weird.
Some people find this feeling very frightening. I dont really, but it can
be disorientating, and of course if you are having a full on panic attack,
then its scary.