ASVAB · Word Knowledge · 5 min read
Prefixes and Suffixes
- Define prefixes and suffixes and explain how they alter the meaning or part of speech of a root word.
- Recognize common negative, number, directional, and qualifying prefixes to deduce the meaning of unfamiliar vocabulary.
- Use noun, adjective, and verb suffixes to determine a word's grammatical role and eliminate incorrect answer choices on the ASVAB.
The Building Blocks of Words on the ASVAB
The Word Knowledge (WK) subtest measures your vocabulary skills. Together with Paragraph Comprehension (PC), Arithmetic Reasoning (AR), and Mathematics Knowledge (MK), your Word Knowledge score is used to calculate the Armed Forces Qualification Test (AFQT) score. A stronger Word Knowledge score can help improve scores used for eligibility, but it does not by itself guarantee more career options; each military branch sets its own requirements, which can change.
When encountering challenging vocabulary, you do not need to memorize every single term in the dictionary. Instead, you can look for familiar building blocks. A prefix is a letter or group of letters affixed to the beginning of a root word to alter its meaning. A suffix is a letter or group of letters affixed to the end of a root word to modify its meaning or change its part of speech.
By breaking an unknown term into its component parts, looking for a familiar prefix, suffix, and base or root word, you can make an educated guess about the word's core definition. Once you form a clear hypothesis about what the word means, you can check your guess against the given answer choices to find the best match.
Common mistakes
- Assuming every identical letter cluster is a prefix: not all matching letter groups are morphemes. For example, the 'un-' in 'under' or 'uncle' is simply part of the root word, not a negative prefix.
- Confusing 'inter-' and 'intra-': 'inter-' means 'between' or 'among' people, places, or things (as in 'interstate'), while 'intra-' means 'within' (as in 'intramural').
- Ignoring the part of speech indicated by the suffix: selecting an action (verb) or a person (noun) when the tested word ends in an adjective suffix like '-able' or '-ous' is a common trap.
- Overlooking spelling changes in the negative prefix 'in-': it commonly appears as 'im-' before 'b', 'm', or 'p', 'il-' before 'l', and 'ir-' before 'r', as in 'imbalance', 'illicit', and 'irreparable'.
Key points
- Word Knowledge combines with Paragraph Comprehension, Arithmetic Reasoning, and Mathematics Knowledge to determine the AFQT score.
- Prefixes attach to the beginning of roots to adjust meaning, while suffixes attach to the end to modify meaning or shift the part of speech.
- Negative and reversal prefixes include 'un-', 'non-', 'dis-', 'mis-', 'mal-', 'anti-', 'contra-', 'counter-', 'de-', and the variable set 'in-', 'im-', 'il-', and 'ir-'.
- Prefixes can indicate specific numbers ('uni-', 'bi-', 'tri-', 'quadr-'), quantities ('multi-', 'semi-'), time ('pre-', 'post-'), or spatial orientation ('inter-', 'intra-', 'sub-', 'trans-', 'circum-').
- Suffixes often provide clues to a word's part of speech: '-tion' commonly forms nouns, '-ous' commonly forms adjectives, and '-ize' commonly forms verbs, but an ending such as '-ate' does not always identify a verb.
- Not every matching opening letter group is a prefix; check whether it contributes its usual meaning, remembering that a genuine root need not be a stand-alone word (e.g., 'un-' in 'unarmed' versus 'uncle').
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