A negative look-ahead would meet that particular requirement. SSCCE:

use strict;
use warnings;

use Test::More;

my @stopwords = qw/foo sous bar/;
my ($rx) = map qr/(?:$_)/, join "|", map qr/\b\Q$_\E\b(?!-)/, @stopwor
+ds;

my @stop = (
    'foo is good',
    'so is sous'
);

my @go = (
    'sous-alimentation',
);

plan tests => @stop + @go;

for my $str (@stop) {
    like ($str, $rx, "$str matched");
}
for my $str (@go) {
    unlike ($str, $rx, "$str not matched");
}
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