Unfortunately, the definition of the \w character class does not match what natural languages consider as "word characters". See also perlre.

Example:

/tmp>cat 1174444-mod.pl
#!/usr/bin/env perl
use strict;
use warnings;

my @AoA = (
    ['first word', 'greek latin'],
    ['alpha omega', 'beta test'],
    ["don't forget", "can't work", "won't fix" ],
    ["Kindergärten Kindergarten"]
);
my @firsties;

for my $outer (@AoA) {
    for my $inner (@$outer) {
        push @firsties, $inner =~ /^(\w+)/;
    }
}

print "@firsties\n";

/tmp>perl 1174444-mod.pl
first greek alpha beta don can won Kinderg

/tmp>perl -v

This is perl 5, version 18, subversion 1 (v5.18.1) built for x86_64-li
+nux-thread-multi

Copyright 1987-2013, Larry Wall

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using "man perl" or "perldoc perl".  If you have access to
+ the
Internet, point your browser at http://www.perl.org/, the Perl Home Pa
+ge.


/tmp>
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Alexander