But observe the singular phenomenon — on approximately the same date several thousand men and women of letters retire to secluded corners to excogitate a thing described as "charm"; each cudgeling his or her head for some variety which can possibly be regarded as original...
-- Upton Sinclair, Money Writes!
I preferred to relate aloud, to excogitate in a lively, external manner, with a flow of invention as useless as was my declamation of it, a whole novel crammed with adventure, in which the Duchess, fallen upon misfortune…
-- Marcel Proust, Swann's Way
Origin:
Excogitate is related to the word cogitate which means "to think." The prefix ex- typically means "out of", but in this case it means "thoroughly."
