Morpheme - is a minimal unit of meaning or grammatical function. The word reopened consists of three morphemes.

One minimal unit of meaning is open, another minimal unit of meaning is re- (meaning ‘again'), and a minimal unit of grammatical function is -ed (indicating past tense). Morphemes should not be confused with syllables. For example, the word elephant has three syllables but is just one morpheme.

Free morphemes - can stand by themselves as single words. These are technically separate English word forms such as basic nouns, adjectives, verbs, etc. When combined with bound morphemes the free morphemes are called ‘stems'. In some words identified stems cannot stand alone and are called ‘bound stems' (receive, deceive, perceive).

Lexical morphemes - set of ordinary nouns, adjectives and verbs that carry the ‘content' of the message we convey. This is an ‘open' class of morphemes because we can add new words to the language easily (girl, tiger, sincere, play, e-mail, blog).

Functional morphemes - consist of functional words in the language such as conjunctions, prepositions, articles, and pronouns. This is a ‘closed' class of morphemes because we almost never add new functional words to the language (and, he, the, above).

Bound morphemes - cannot stand alone and are typically attached to another form. They can be both prefixes and suffixes (re-, un-, dis-, pre-, -ness, -less, -ly).

Derivational morphemes - make new words of a different grammatical category from a stem (noun care can be changed to adjectives careful, careless; and the latter can be changed to an adverb carelessly).

Inflectional morphemes - indicate aspects of the grammatical function of a word. There are eight inflectional morphemes in English. They are all suffixes. Two inflectional morphemes can be attached to nouns, -‘s (possessive case), -(e)s (plural). Four inflections can be attached to verbs, -(e)d (past tense), -ing (present participle), -en (past participle), -s (3rd person singular). Two inflections can be attached to adjectives, -er (comparative), -est (superlative).

In the sentence The child's wildness shocked the teachers, we can identify eleven morphemes.

The                 child               -‘s                    wild                 -ness

functional      lexical             inflectional          lexical             derivational

shock            -ed                  the                  teach              -er                   -s

lexical           inflectional       functional         lexical             derivational        inflectional

Source: Yule, G. (2006). The Study of Language. (Third Edition) Cambridge, UK: Cambridge University Press, (pp. 65-66).