The ASVAB's 10 components are general science (GS), arithmetic reasoning (AR), word knowledge (WK), paragraph comprehension (PC), mathematics knowledge (MK), electronics information (EI), auto information (AI), shop information (SI), mechanical comprehension (MC) and assembling objects (AO). WK and PC directly test your vocabulary skills. In WK, you're generally provided a word and must choose a word with the most similar definition, from four other words. PC asks for the meaning of a word within a specific provided context from a selected excerpt.
It's best to prepare for the ASVAB's vocabulary testing by taking a practice exam and getting a feel for the test. In addition to numerous printed practice guides, from test preparation companies such as Kaplan or McGraw-Hill, many websites offer sample questions or complete tests online. Complete as many practice questions as possible and identify the types of words you find most difficult.
Adults learn words by having read them in multiple contexts, so the best way to build vocabulary is with increased reading. To learn words quicker and efficiently, keep a dictionary on hand and look up words you don't recognize or that are used in an unfamiliar context. If you're already an avid reader, consider broadening the materials you read to more formal publications. Examples include nationally distributed news journals and magazines.
Etymology is the study of how individual words obtained their meanings through history. Though English is historically related to German, most English words evolved from Latin and Greek roots. You don't have to learn Greek or Latin to improve your vocabulary; there are books and websites that list the most common Latin and Greek word roots that appear in English. By studying these word roots, especially prefixes and suffixes, you can increase your likelihood of correctly guessing the meaning of unfamiliar words. For example, by learning that "cor" is the Latin root word for "heart," you could correctly guess on the ASVAB that "coronary" is a word that refers to the heart.