Derivational morphology
Consider the words in (1a, b), all of which contain the word believe plus at least one other morpheme. Intuitively, we might say that the examples in (1a) are really just different forms of the same word, while the forms in (1b) are actually different words, which are “derived from” believe.
(1) base: believe
a believe-s, believe-d
b believ-er, un-believ-able
What is this intuition based on? One obvious factor is that the words in (1b) belong to different syntactic categories from believe: the first is a noun; the second an adjective. The words in (1a) on the other hand are both verbs, just as believe is. Another important factor is that the words in (1b) have meanings which are in some way different from the meaning of believe. In defining the (1b) forms we need to add some extra components of meaning: “a believer is a person who believes”; “something which is unbelievable is difficult or impossible for us to believe.” But the forms in (1a) mean essentially the same thing as the base form (believe).1 The suffixes in these forms simply add information about when it is appropriate to use that specific form, e.g. “believes describes the present time, but believed refers to sometime in the past.”
A more precise way to express this difference is to say that believe, believes, and believed are all forms of the same LEXEME, whereas believer and unbelievable are distinct lexemes. In Criteria for distinguishing inflection vs. derivation, we will present a more careful explanation of the term LEXEME, but intuitively it refers to all of the “variant forms” of a single lexical item.
The kind of affixation exhibited in (1a) is commonly referred to as INFLECTIONAL MORPHOLOGY; that in (1b) DERIVATIONAL MORPHOLOGY. The basic definition of these terms is that derivational morphology changes one word (or lexeme) into another, while inflectional morphology creates different forms of the same lexeme. We will discuss a wide variety of derivational affixes from a number of different languages. But first we need to introduce some additional terminology.
1. The term “base” is used in a non-technical sense meaning simply the form to which an affix is added. A base may be either a root or a stem.
