A word and its part: roots, affixes and their shapes
Smaller part of word generally called by morpheme
Morpheme can be thought of as the minimal unit of morphology
Morphemes have two characteristic. First, morphemes must be identifiable from one word to another word. Second morphemes must be contributed in some way to the meaning of the whole word.
Allomorph concerned as it is with differences in how a morpheme is pronounced
The identification of morpheme dependent on their meaning.
Morphemes are not merely the smallest units of grammatical structure but also the smallest meaningful units.
A complex word may consist
1. free + bound
2. bound + bound (free root and bound root)
3. free + free
In the native Germanic portion of vocabulary, the roots of a complex word usually free. Of the non-root morpheme in the words that we have looked at so far, those that precede the root (like en-in enlarge) are called prefixes, while those that follow it are called suffixes (like –ance in performance, -ness in whiteness, and -able in readable). We have encountered far more suffixes than prefixes, and that is not an accident: there are indeed more suffixes than prefixes in English. An Umbrella term for prefixes and suffixes (broadly speaking, for all morphemes that are not roots) is affix.
Affixes are necessary bound.
Affixes are indeed always bound, but it is not the case that roots are always free
Prefix root-combinations: the prefixes and roots that they comprise are identifiable without reference to meaning.
Lexical conditioning to which these morphemes are subject is of a particularly strong kind: none of them ever occurs except in complex words that require dictionary listing.