How can you recognize the root and then know the root meanings of these words? How do you know what the prefixes or suffixes of these words?
Unlike the prefix, having the ending on the word usually won't distort the meaning of the basic word significantly. To state this more emphatically, the suffix should change the word, but not its essence, but the prefix is very likely to change and even reverse the essential meaning of the word. Taking an example from "A Little Etymology," which presents a working definition of suffix (please see A Little Etymology if you don't have a clear sense of suffix) the word "please" has "e" as a suffix. The word "pleasure" has "ure" as a suffix. The positive aspect, also found in pleasant, in please and pleasure is present even when you've stripped the suffix. In contrast, displease has a prefix that dramatically changes the meaning of the word. Take the dis- off and you have the opposite meaning.
Well and good, you might say, but how do I know dis- is a prefix?
If you have a word like polyandry (having many husbands), the prefix is poly- meaning many.
- If you look in a dictionary, you can see many words beginning with poly-. That is an excellent way to spot a prefix.
What is left is -andry. This is not a word in English. Y is a common ending in English words, but if you take it off, you're left with andr- which is definitely not an English word. At this point, since you have a word stripped of its prefix and ending, you can look in a Latin or Greek dictionary to see if you can find something that begins andr. The word comes from andros and means man.
- Although English words do make use of multiple prefixes, as in the classic "anti-dis-establishmentarianism", most English words have one prefix at most and a root word.
If you start looking for prefix after prefix in the same word, you are likely to land in trouble. For example, in polyandry, you might see the poly-, strip it off, then see the a- or an- and think it's one of those negating forms as in theist/atheist archist/anarchist. If you strip off this "second" prefix, you have "dr" which doesn't look like and isn't an English word or root at all. So stick with stripping off one prefix until you're sure you understand.
Note that prefixes are usually prepositions, adverbs, or adverbs, rather than nouns, like andros (man).