Regex Confusion

Hello,
in the Regex Documentation, it says that [^abc] matches for everything except “a”,“b”,and “c”. But is there a way we can match for everything except “abc”? such that for example a single appearance of ‘a’ would still match.

As i researched it , i figured out excluding certain words is not easy in regex, but I got something like this
\b(?!abc\b)\w+

The relevant part is the negative lookahead:

(?!...)

It matches only if no ... follows.
This is a lookahead (an expression of the Lookaround group).
The regex part inside the group is not part of the matched result (a zero length group) but restricts the matched results in certain ways.

Not every implementation of RegEx supports Lookarounds like the negative lookahead as they are quite costly to parse.
But Java does.

Here a quick overview of Lookarounds.
Longer tutorial.