Inflectional morphemes are bound morpheme
s that alter the grammatical state of the root
. They do not carry any meaning on their own, as is the nature of bound morphemes, but serve a critical function in inflected languages such as English. (It should be noted, however, that English is more of an analytic language
, one that depends more heavily on sentence structure than conjugation
s and declension
These bound morphemes express such concepts as tense, number, gender, case, aspect, and so on. In other words, they are grammatical markers. Unlike derivational morphemes they do not change the syntactic category of a word. A verb remains a verb no matter the inflectional morpheme, and a noun a noun. Additionally, they cannot be joined to incomplete morphemes. For example, you can add the derivational bound morpheme "atic" to "unsystem" to get "unsystematic." You cannot, however, add a possessive marker to make "unsystem's."
English used to be highly inflected and had a very rich variety of inflectional morphemes. Now, however, there are only eight left. They are:
-s third person singular present She waits at home.
-ed past tense She waited at home.
-ing progressive She is waiting at home.
-en past participle She has eaten the donut.
-s plural She ate the donuts.
-'s possessive Lisa's hair is short.
-er comparative Lisa has shorter hair than Mary.
-est superlative Lisa has the shortest hair.
Inflectional morphemes typically follow deriviational morphemes in the hierarchy of morpheme structure. IE, they occur last, at the end of the morpheme, not before any derivational morphemes. It is, for example, "unlikelyhoods" for more than one unlikelyhood, not something like "unlikelyshood."
Some words do not take the regular inflectional morphemes; they are irregular, or, more technically, suppletive. The past tense of "buy" is not "buyed," but "bought." This is an irregularity that is simply memorized.
The examples were taken from An Introduction to Language, Sixth Ed. by Victoria Fromkin and Robert Rodman.