If you want to define keys and don't care about values (i.e. you're only going to see if a key exists), you can use undef:
my %word;
undef @word{qw(AALIYAH AARON ALEX ...)};
print "exists!\n" if exists $word{ALEX};
# Or if you want to make sure the values are set to undef:
my %word;
@word{qw(AALIYAH AARON ...)} = undef;