A slightly more extensive type of assimilation occurs in the series 'comparable', 'context', 'congregate' [...] Though this prefix has three forms /kam-, kan-, kaŋ/, their distribution can be phonologically defined [...] We may call the forms morphemic alternants or allomorphs. - Nida (1949), a pag.14
[...] alternant forms of a single morpheme [...] - Nida (1949), a pag.14