C is for

Look it up in a dictionary and if you find anything at all you are likely find it defined something like this:
Coetanean -- a synonym for contemporary. Along with contemporary, the word coeval might appear as English translations of the Spanish term coetaneo. But in the work of the extraordinary Spanish thinker Ortega y Gasset contemporary and coetanean have very different meanings. These notions appear with a similar sense in the in the Siloist version of the generational dialectic.

Back in the day (when I first encountered Silo’s teachings) you’d have found a definition in the materials of the time something like this:

COETANEAN: Of the same age. Within the generational dialectic, coetaneans are those individuals that belong to the same generation although their particular ages differ. Ortega y Gasset differentiates between coetaneans and contemporaries, explaining that the latter are members of different generations but live in a same historical moment.
Siloism H. Van Doren: Aconcagua Press, 1972