Alternation (linguistics)

In linguistics, an alternation is the phenomenon of a phoneme or morpheme exhibiting variation in its phonological realization. Each of the various realizations is called an alternate. The variation may be conditioned by the phonological, morphological, and/or syntactic environment in which the morpheme finds itself.

Alternations provide linguists with data that allow them to determine the allophones and allomorphs of a language's phonemes and morphemes and to develop analyses determining the distribution of those allophones and allomorphs.

Phonologically conditioned alternation
An example of a phonologically conditioned alternation is the English plural marker commonly spelled s or es. This morpheme is pronounced, , or , depending on the nature of the preceding sound.


 * 1) If the preceding sound is a sibilant consonant (one of, or ), the plural marker takes the form . Examples:
 * 2) *mass, plural masses
 * 3) *fez, plural fezzes
 * 4) *mesh, plural meshes
 * 5) *mirage, plural mirages
 * 6) *church, plural churches
 * 7) *bridge, plural bridges
 * 8) Otherwise, if the preceding sound is voiceless, the plural marker takes the form . Examples:
 * 9) *mop, plural mops
 * 10) *mat, plural mats
 * 11) *pack, plural packs
 * 12) *cough, plural coughs
 * 13) *myth, plural myths
 * 14) Otherwise, the plural marker takes the form.
 * 15) *dog, plural dogs
 * 16) *glove, plural gloves
 * 17) *ram, plural rams
 * 18) *doll, plural dolls
 * 19) *toe, plural toes

Morphologically conditioned alternation
An example of a morphologically conditioned alternation is found in French, where many adjectives have a consonant at the end in the feminine gender that is missing in the masculine:
 * masculine petit, feminine petite "small"
 * masculine grand, feminine grande "big"
 * masculine gros, feminine grosse "tall"
 * masculine joyeux, feminine joyeuse "merry"
 * masculine franc, feminine franche "sincere"
 * masculine bon, feminine bonne "good"

Syntactically conditioned alternation
Syntactically conditioned alternations can be found in the Insular Celtic languages, where words undergo various initial consonant mutations depending on their syntactic position. For example, in Irish, an adjective undergoes lenition after a feminine singular noun: In Welsh, a noun undergoes soft mutation when it is the direct object of a finite verb:
 * unmutated mór "big", mutated in bean mhór  "a big woman"
 * unmutated beic "bike", mutated in Prynodd y ddynes feic  "The woman bought a bike"