Base words exist on their own as a recognizable word in the English language. For example, "inspect" is the base word of inspection, inspected, inspecting and inspector. Root words are portions of a base word that do not stand alone and have no meaning by themselves in the English language and are usually derived from Greek or Latin. Continuing the previous example, the root word of "inspect" is "spec," from the Latin word "spectare" meaning see.
Affixes are word parts added before or after the root word to construct a new word. Word parts that come before the root word are prefixes, such as pre-, non-, un and dis-. Word parts that come after the root word are suffixes, such as –tion, -ing, -al and –able.
It’s in the Syllables
Early reading focuses on one- or two-syllable words composed almost entirely of base words. Words like "cat," "dog," "ball," "run" and "jump" are all base words. As the reading difficulty increases, so does the complexity of the words. Multisyllabic words consist of a root word and one or more prefixes and/or suffixes. Multisyllabic words may or may not have a base word. For example, “invisible” consists of the prefix in-, the root word "vis" and the suffix –ible. However, “nonfictional” consists of the base word "fiction", the prefix non-, the root word "fic," the suffix –tion and the suffix –al.
Words with similar root words have similar meanings. The application of different suffixes and prefixes change the definition of the word. Consider this example from Education.com. The Latin word "vis" means to see. When you read the words "vision," "invisible" and "visitation," you can reasonably infer that all of the words have something to do with seeing, even if you do not know their exact meaning. The same would be true for the root word" tract" meaning to pull or drag. The words "attractive," "subtract" and "tractor" all belong to the same meaning family.
Real World Example
Learning to recognize base words and root words is a primary goal when preparing to take the SAT test. It's impossible to know the meaning of every word in the English language. If you read a word but do not know it, you can use knowledge of root words to infer a possible meaning. For example, on the SAT vocabulary test, you are asked to choose a synonym for the word “magnanimous.” You may not know the meaning of the word but you do know the meaning of the words "magnitude" and "magnificent" -- words that have to do with greatness or power. From the list of possible words, you select "bountiful" because you define it as having plenty or a great amount.