Affix

Affixes are divided into several categories, depending on their position and their role with reference to the root. The most important positional categories are:

• prefix (PFX) - Appears at the front of the root (such as "un-" in "undo", or "re-" in "rewrite")
• suffix (SFX) - Appears at the back of the root (such "-s" in "tables", or "-er" in "writer")
• infix (IFX) - Appears within the root (very rare in English, such as "-ma-" in "sophistimacated")
• circumfix (CCX) - Appears at the front and at the back of the root (very rare in English, such as "a-" + "-ed" in "ascattered")

As for their roles, there are two main different types of affixes:

• inflectional affix - assign grammatical properties (such as number, gender, tense, person) to the root in order to form the different word forms of the same lexeme ("-s" in "tables", "-ed" in "loved")
• derivational affix - form a new lexeme by modifying the meaning (and sometimes the category) of the root ("un-" in "unhappy", "-ness" in "happiness").