Operands are arguments to operators. You can take any variable, constant or object you want and pass it to any operator you want.

With overload you can give existing operators new meaning for some objects as operands.

In Perl 6, you can make new operators simply by declaring them:

sub postfix:<!>(Int $n) {  [*] 1..$n }

say 6!;  # 120
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In Perl 5, there is no simple way. Filter::Simple and other source filters require much more work to declare new operators, and the result is generally rather brittle.

Devel::Declare makes creating new syntax a bit more robust, but it's just a gradual improvement.

Does use overload sound like what you are looking for? As in ...

...
use overload
      "-"    => \&minus,
      "+"    => \&plus,
      "*"    => \&mult,
      "bool" => \&bool;
...
sub plus {
    my $u = shift;
    my $v = shift;
    return new Vector2D ( 
        $u->getx() + $v->getx(),
        $u->gety() + $v->gety()
    );
}
...
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feature::qw_comments makes a new keyword called qw. Ok, there's already one called qw, but the module completely replaces it. The same API can be used to make entirely new keywords.

It uses an interface added to Perl in 5.14. This interface is much more resilient than source filters, and much more usable than Devel::Declare.

It cannot be used to create symbolic (e.g. "+") operators, or anything but prefix operators/keywords (e.g. KEYWORD SOMETHING, not SOMETHING KEYWORD or SOMETHING KEYWORD SOMETHING).

It can be used to introduce a section of code that's not Perl, just like m/ introduces a section of code that's a regexp, not Perl. For example, one could use this interface to create a keyword that indicates the start of a snippet of Lisp grammar.

Ah, as both of you understood I ment operator, but wrote something else. Thanks for the pointer to Perl6. Maybe this is what I so vaguely remember having read about