What is a Prefix?

Prefixes are common letter combinations at the beginning of words.


In this video, we want to go over prefixes. Prefixes are short, little sections of words that come before the root of a word and help you understand what the word means. They add an extra nuance to the word. Why prefixes, and suffixes for that matter, are important (prefixes coming before the root of the word and suffixes being short, little endings after the word) is that if you know your basic prefixes and suffixes, they help you determine the meaning of a word. They’re important clues, especially if you’re taking a standardized test where they say, “We want you to find the word with the opposite meaning.”

Sometimes just knowing the prefix can give you enough of a clue, even if you don’t know what the root means, to find the opposite. We’ve got a few examples on the board, and we want to go through those briefly just to show you the importance of prefixes, how they can help you in your test-taking strategies, and how they can help you understand the meanings of words. Prefixes give clues as to a word’s meaning. Knowing them can help you find the word with the opposite meaning on a test.

Prefixes like pre-. Here, we think “preoperative”. “Pre-op” means “before the operation”. “Prescient”, pre- meaning “before” and -scient comes from the word science, which means “knowledge”. “To know ahead of time”. “Prescient” is to know ahead of time. “Pregame show”, the part that comes before the game. Pre- means “before”. The opposite of pre- is post-. Postoperative care is the care that happens after the operation. The postgame show is the show that happens after the game. Pre- is “before”, post- is “after”. If you realize this opposite, then if you see a word that’s got a pre- prefix on it, then you look for a word with the post- prefix on it if the test is asking you to find the opposite.

Another thing would be pro- and de-. Pro- means “for”, as in “pro-life”. Someone who is “pro-life” is for life. De- is the negation. “Deconstruction”. To deconstruct is the negation of construction. Construction to build up, deconstruct to destroy it. Pro-, meaning for, de- is usually a negation. Pre- is before, post- is after. Knowing your prefixes can be critical, especially if you’re not sure of the whole word. You can say, “Let me break this word up into its prefix, its root, and its suffix and see if I can’t decode just from that minimal information the proper answer on the other side.” Obviously, when you’re taking a test if you know the right answer, you always go with the right answer.

If you’re struggling, if you’re not sure, this is a strategy you can use. You can look at the word, break it down, and say, “Here’s the prefix and I know it means this. I’m being asked to find the opposite. What’s the opposite of this prefix?” Then I’ve got my answer more than likely. Caution, though. Caution. Con- and pro- are opposites, but “congress” is not the opposite of “progress”. Some people might disagree as more of a joke in terms of Congress being the opposite of progress. Con- and pro- are opposites, but you have to know and be careful sometimes.

That’s been just a basic introduction and overview of the importance of prefixes as a test-taking strategy of knowing what they mean to help you determine the meaning of a word and to assist you if you’re being asked to look for the opposite. If you know what the prefix means, and you know what the opposite that prefix is it makes it a snap to find the right answer.



by Mometrix Test Preparation | Last Updated: August 14, 2019