Prefixes are added to the beginning of the base or root word to change its meaning. For most prefixes, we do not change the spelling of the base word; we simply add the prefix to the beginning.

Prefixes are used three different ways:

Prefixes are added to the beginning of a base word. These words can be used with or without prefixes. In this case, the prefix can change the meaning of the base word, as in adding UN- to “button” to get “unbutton”.

Prefixes can be used with a root that is not used without the prefix, as in adding Prefix IN- to root “ject”, to get “inject”.

Some prefixes exist as stand alone words, as in “up”, which also can be used as a prefix, as in “upstanding”.

A few prefixes are called “chameleon prefixes” because we change how the prefix itself is spelled based on the first letter of the root or base word. These include A-, OB-, EX-, CON-, SUB-, and IN-. Most often, even these prefixes do not change the spelling of the base word, as we simply add the prefix to the beginning of the root or base.