#!perl

use strict;
use warnings;

my %acronyms = (
   'HTML'    => "Hypertext Markup Language",
   'ICBM'    => "Intercontinental Ballistic Missile",
   'EEPROM'  => "Electronically-erasable programmable read only memory",
   'SCUBA'   => "Self Contained Underwater Breathing Aparatus",
   'FAQ'     => "Frequently Asked Questions",
   'LCARS'   => "Library Computer And Retrieval System",
   'NASA'    => "National Aeronautical and Space Administration"
);

my $regex;
{
   my $temp = join '|', map quotemeta, keys %acronyms;
   $regex = qr/($temp)/o;
}

while (<>) {
   s/$regex/$1 ($acronyms{$1})/g;
   print;
}