Bound and free morphemes
In general linguistics, a bound morpheme is a morpheme that can appear only as part of a larger expression; a free morpheme is one that can stand alone. A bound morpheme is a type of bound form, and a free morpheme is a type of free form.
Roots and affixes
Many roots in English are free morphemes, but others are bound are referred to as compound words.Affixes are bound by definition. English language affixes are almost exclusively prefixes or suffixes: pre- in "precaution" and -ment in "shipment". Affixes may be inflectional, indicating how a certain word relates to other words in a larger phrase, or derivational, changing either the part of speech or the actual meaning of a word.
Cranberry morphemes are a special form of bound morpheme whose independent meaning has been displaced and serves only to distinguish one word from another, like in cranberry, in which the free morpheme berry is preceded by the bound morpheme cran-, meaning "crane" from the earlier name for the berry, "crane berry".
An Empty Morpheme is a special type of bound morpheme with no inherent meaning. Empty morphemes change the phonetics of a word but offer no semantic value to the word as a whole.
Examples:
| Morpheme | Morpheme Form | Morpheme Meaning |
| fact- | Free Morpheme | An idea or concept, usually proven true with supporting evidence, that has been socially accepted. |
| -u- | Bound Morpheme | No meaning. |
| -al | Bound Morpheme | A type of, pertaining to, related to, etc. Creates an adjective form of the noun it supplements. |
| Morpheme | Morpheme Form | Morpheme Meaning |
| speed- | Free Morpheme | The rate which an object covers distance. |
| -o- | Bound Morpheme | No meaning. |
| -meter | Bound Morpheme | A measurement device. |
Word formation
Words can be formed purely from bound morphemes, as in English permit, ultimately from Latin because of the largely morphosyllabic script, but disyllabic words exist that cannot be analyzed into independent morphemes, such as 蝴蝶 húdié 'butterfly'. Then, the individual syllables and corresponding characters are used only in that word, and while they can be interpreted as bound morphemes 蝴 hú- and 蝶 -dié, it is more commonly considered a single disyllabic morpheme. See polysyllabic Chinese morphemes for further discussion.Linguists usually distinguish between productive and unproductive forms when speaking about morphemes. For example, the morpheme ten- in tenant was originally derived from the Latin word tenere, "to hold", and the same basic meaning is seen in such words as "tenable" and "intention." But as ten- is not used in English to form new words, most linguists would not consider it to be a morpheme at all.
Analytic and synthetic languages
A language with a very low ratio of morphemes to words is an isolating language. Since such a language uses few bound morphemes, it expresses most grammatical relationships by word order or helper words, so it is an analytic language.In contrast, a language that uses a substantial number of bound morphemes to express grammatical relationships is a synthetic language.