Defense Language Aptitude Battery (DLAB) - Paperbackby Passbooks (Compiled by) The Defense Language Aptitude Battery (DLAB) Passbook(R) prepares you for your test by allowing you to take practice exams in the subjects you need to study. It provides hundreds of questions and answers in the areas that will likely be covered on your upcoming exam, including but not limited to: spelling; word meaning; understanding and interpreting written material; foreign language spelling and meaning; writing skills;