The words "category" and "monad" existed already in philosophy. The usage of the terms in category theory seems to be slightly influenced by the philosophical meaning, but actually the concepts are by far not the same.
So, why did Eilenberg and Mac Lane choose the name "category", out of many possible, what's the story?
And who and why choose the term "monad", for the monads of category theory? (I guess that comes from "monoid", but is it true?)
Any reference on these mathematical etymologies would be also highly appreciated.