When you are reading, you will come across unfamiliar words. It is often possible to guess the meanings of these words if you understand the way words in English are generally formed.
An English word can be divided into three parts: a prefix, a stem and a suffix. Pre- means 'before'; a prefix, therefore, is what comes before the stem. Consider as an example, the prefix de- (meaning 'reduce' or 'reverse') in a word like demagnetize (meaning 'to deprive of magnetism'). A suffix is what is attached to the end of the stem. Consider as an example the suffix -er (meaning 'someone who') in programmer ('the person who programs'). Both prefixes and suffixes are referred to as affixes.
Prefixes usually change the meaning of the word; for example, un-changes a word to the negative. Unmagnetizable means 'not capable of being magnetized'. Suffixes, on the other hand, change the word from one part of speech to another. For example, -ly added to the adjective quick gives the adverb quickly. Let us now consider some suffixes and their usual meanings.