use Data::Dumper;       
#          Two strings,   single blanc, two strings,   double blanc
my @words=("abcd","efgh", "",           "jklm","nopq", "", "");
my $combined;
my @combinations;
for my $word (@words){
  if ($word){
    $combined .=$word;
  }
  else{
    push @combinations, $combined if $combined;
    $combined="";
  }
}
@words=@combinations;
print Dumper\@words;