"redices" and "indices"

[Dave Long]

Of possible interest is the general linguistic rule that irregular forms  
are like footpaths in a lawn -- they occur in frequently-used areas, but  
disappear with disuse; as a domain becomes obsolete, its vocabulary goes  
regular.  This pattern covers both the pedants (for whom the classical  
form is, like the well-trampled earth of an abandoned path, a sign that a  
word was once frequently wrought, even if the current population never  
uses it) and the hackers (for whom the novel form is, like the fresh cut  
of a new singletrack, a declaration that they frequently work with a word,  
even if the general population never uses it).

-Dave