The Morpheme is the smallest unit of a language that can carry meaning.
Morphology is the study of words. The morpheme is the smallest unit of a language that can carry meaning.
Hence, every uncompounded word in English is a morpheme. The word "me" is one morpheme. The word "Mississippi" is also one morpheme.
Morphemes are certainly a major part of our lexicon (vocabulary) and we want to facilitate their acquisition as much as possible. We will discuss how later.
"Me" and "Missisippi" are called free morphemes because when you hear them by themselves, they have symbolic significance.
There is another smaller class of morphemes for which that isn't the case.
If you hear me say "ssssss," you would probably classify it as an English phoneme.
But any meaning you derived from this would be from the non linguistic channel--as a sign in an emotional graded communication.
NOTES: Get some in depth discriptions of morphemes.
NOTES: Still more information on Morphemes.
NOTES: More information that you could use in a lifetime on Morphemes.