I have always considered myself relatively learned. not always smart, but at least intelligent.
in the course of two weeks, I have uncovered two words from two different authors, that I have not ever seen.
for instance today:
Raymond Feist in his book "King of Foxes"
introduced me to the word:

DEFENESTRATION
Main Entry: de·fen·es·tra·tion
Pronunciation: (")dE-"fe-n&-'strA-sh&n
Function: noun
Etymology: de- + Latin fenestra window
: a throwing of a person or thing out of a window

used by premedieval/tribal groups as a means of execution: being thrown from height down onto rocks below

now last week
Steven Brust in three of his novels
"Lord of Castle Black," "Dragon," and one other, possibley "Paths of the Dead," the books title slips my mind used the word
PERSPICACIOUS
Main Entry: per·spi·ca·cious
Pronunciation: "p&r-sp&-'kA-sh&s
Function: adjective
Etymology: Latin perspicac-, perspicax, from perspicere
: of acute mental vision or discernment : KEEN
synonym see SHREWD
- per·spi·ca·cious·ly adverb
- per·spi·ca·cious·ness noun
- per·spi·cac·i·ty /-'ka-s&-tE/ noun

Non I have to say while truly enjoying the works of Steven Brust, it is difficult to have an understanding of such a word when it is used in such simplicity such as:
"You are perspicacious."
no other context!
oh yes!?!?!?!?!?!?!?!
I asked at least 8 other individuals that happened to be in "earshot" ie clearcom during a show
between us 8 we held a total of 7 undergrad degrees, 2 graduate degrees, 4 associate degress, two NC teaching licensures, and at least one major in english if not a minor in english.
Of our learned mass brain power...
non of us had heard of the word
I challenge you Mr.Brust, for I am guessing that you have the joy of those abominable word a day calendars.

such a statement as "You are perspicacious" is more worthy of fortune cookie nomenclature than in scifi/fantasy.