An article on AVClub in January introduced me to a new word - concision. In defence of short story writing as a stand-alone career (asserting the right of authors to not write novels), Kevin McFarland said: 'There is nothing wrong with concision in fiction.'
When I read this word, I knew it meant the writing was concise, but I had thought the noun for this concept was conciseness.
The Australian Macquarie Dictionary defines conciseness as 'the quality of being concise' and concision as 'concise quality; brevity; terseness'. So I guess I can add this new word to my vocabulary as a synonym for the word I already knew.
WordReference Forums, which appears to be north-American based, has a discussion of these two words, and the consensus seems to be that conciseness is the more usual term, with concision seeming pretentious and somewhat old-fashioned. One interesting comment is that concision implies an action (like words such as decision, incision, division), while conciseness implies a quality.