Affix (Grammar)

Definition

An affix is a bound morpheme which adds lexical or syntactic information to a root or stem.

Some languages have zero affixes, whereby meaning is conveyed by the absence of an affix.

Affix and Root or Stem

Here is a table that compares and contrasts affixes and roots or stems:

Affixes	Roots or Stems
Usually have grammatical meaning (but derivational affixes may have lexical meaning).	Usually have lexical meaning.
Are usually members of closed syntactic classes.	Are usually members of open syntactic classes.
Are always bound.	May be bound or free.

More specific concepts within affix (grammar).