I have a pattern with a small list of words that are illegal to use as nicknames set in a pattern variable like this:

```
$pattern = webmaster|admin|webadmin|sysadmin

```

Using `preg_match`, how can I achieve so that nicknames with these words are forbidden, but registering something like "`admin2`" or "`thesysadmin`" is allowed?

This is the expression I have so far: 

```
preg_match('/^['.$pattern.']/i','admin');

```

// Should not be allowed

Note: Using a `\b` didn't help much.