#!/usr/bin/perl
use 5.012;
use warnings;

my %matches;
my @candidates = qw(Wort1 Wort2 wort3 wort4);

while (my $line = <DATA>) {
    for my $candidate (@candidates) {
	push @{$matches{$candidate}}, $. if ($line =~ m/(^|[\s.;])\Q$candidate\E([\s.;]|$)/i);
    }
}

while (my ($candidate, $linenos) = each %matches) {
    say "$candidate found on line ", join(", ", @{$linenos});
}

__DATA__
aaaaaaaaaaaaaaaaaaaaa.wort1;aaaaaaaa
bbbbbbbbbbbbbb wort2 bbbbbbbbbbbbbbb
ccccccccccccccccccccc wort3 cccccccc
ddddddddddd wort1 dddddwort2dddddddd
eeeeeeeeeeeeeeeeeeee wort4 eeeeeeeee