morpheme
smallest meaningful unit in a language. Fucntins as alinguisitic sign. All words are morphemes or combinations of more than one morpheme. Not all morphemes function as stand alone words.
free/independent morpheme
can occur by itself
bound morpheme
can only occur in combination with one or more additional morphemes. Prefixes and affixes are most common bound morphemes
Stages of morpheme Acquisition
Stage 1: ing, s, is, am, are
Stage 2: is, articles
Stage 3: irregular past tense verbs
Stage 4: regular past tense verbs, third person singular, possessives