Definitions
morpheme: a combination of sounds that have a meaning. A morpheme does not necessarily have to be a word. Example: the word cats has two morphemes. Cat is a morpheme, and s is a morpheme. Every morpheme is either a base or an affix. An affix can be either a prefix or a suffix. Cat is the base morpheme, and s is a suffix.
affix: a morpheme that comes at the beginning (prefix) or the ending (suffix) of a base morpheme. Note: An affix usually is a morpheme that cannot stand alone. Examples: -ful, -ly, -ity, -ness. A few exceptions are able, like, and less.
base: a morpheme that gives a word its meaning. The base morpheme cat gives the word cats its meaning: a particular type of animal.
prefix: an affix that comes before a base morpheme. The in in the word inspect is a prefix.
suffix: an affix that comes after a base morpheme. The s in cats is a suffix.
free morpheme: a morpheme that can stand alone as a word without another morpheme. It does not need anything attached to it to make a word. Cat is a free morpheme.
bound morpheme: a sound or a combination of sounds that cannot stand alone as a word. The s in cats is a bound morpheme, and it does not have any meaning without the free morpheme cat.
inflectional morpheme: this morpheme can only be a suffix. The s in cats is an inflectional morpheme. An inflectional morpheme creates a change in the function of the word. Example: the d in invited indicates past tense. English has only seven inflectional morphemes: -s (plural) and -s (possessive) are noun inflections; -s ( 3rd-person singular), -ed ( past tense), -en (past participle), and -ing ( present participle) are verb inflections; -er (comparative) and -est (superlative) are adjective and adverb inflections.
derivational morpheme: this type of morpheme changes the meaning of the word or the part of speech or both. Derivational morphemes often create new words. Example: the prefix and derivational morpheme un added to invited changes the meaning of the word.
allomorphs: different phonetic forms or variations of a morpheme. Example: The final morphemes in the following words are pronounced differently, but they all indicate plurality: dogs, cats, and horses.
homonyms: morphemes that are spelled the same but have different meanings. Examples: bear (an animal) and bear (to carry), plain (simple) and plain ( a level area of land).
homophones: morphemes that sound alike but have different meanings and spellings. Examples: bear, bare; plain, plane; cite, sight, site.