The word knowledge subtest is one of the four subtests that make up your AFQT score which determines your eligibility to enlist in the military. This makes it (along with Paragraph Comprehension, Mathematics Knowledge, and Arithmetic Reasoning) one of the most important subtests on the ASVAB.
In addition to making up part of your AFQT score, your word knowledge score is also factored into several line scores for disciplines that require a large vocabulary and good grammar.
The word knowledge subtest measures your vocabulary and the number and types of words you understand. The questions are multiple choice and ask you to identify the meaning, synonym or antonym of a given word. You’ll have 11 minutes to answer 35 questions so you’ll have to work your way through the questions fairly quickly.
The best way to study for the word knowledge subtest is to take a variety of practice tests to expose you to as many potential words as possible and get you comfortable with answering the variety of word knowledge questions that will appear on the test.