Definition
A morphophonemic rule has the form of a phonological rule, but is restricted to a particular morphological environment.
Discussion
Morphophonemic rules are sensitive to their environment, unlike phonological rules. Whenever morphological information is required to specify the environment for an allophonic rule, the rule is morphophonemic.
Examples
- The prefix /in-/ has the allomorphs [il] and [ir]
|
/in-/ + responsible |
irresponsible |
|
/in-/ + logical |
illogical |
The rules n G l / __l and n G r / __r are not phonological rules in English, however. If they were, the prefixes /un-/ and /non-/ would also exhibit this regular pattern, but they do not.
|
/un-/ + responsive |
(*urresponsive) |
unresponsive |
|
/un-/ + limited |
(*ullimited) |
unlimited |
|
/non-/ + retroactive |
(*nor-retroactive) |
non-retroactive |
|
/non-/ + lethal |
(*nol-lethal) |
non-lethal |
Therefore, there must be a morphophonemic rule which determines the allomorphs [il] and [ir] of the prefix /in-/.
Sources 1
- Payne, T. 1997a, 23–24