Morphology is the study of morphemes. video A morpheme refers to the parts of a word that give it its meaning. Morphemes are added to lexemes to make changes in tense, voice, mood, etc. There are bound morphemes (any kind of affix) and free morphemes (standalone words).
The word “unbreakable” has three morphemes:
“un-“, a bound morpheme;
“break“, a free morpheme; and
“-able“, a bound morpheme.
Since “un-” is on the beginning of the word, it is also called a “prefix“. Since “-able” is attached to the end of the word, it is also called a “suffix“. Both “un-” and “-able” are affixes. “break” is also the lexeme.