Every writer should take this word to heart

"If I'd had more time, I'd have written a shorter letter."

-- Mark Twain

concise / kên-sais / adjective

Tersely expressed, written or spoken with the smallest number of words.

Dr. Goodword notes:

If a text may be concise, of course, it may be written concisely (the adverb). Although we attribute conciseness to such texts, concision is a much lovelier word that expresses the same sentiment: a memo written with such concision that it was a pleasure to read.

History: Concise is the English revision of Latin concisus, the past participle of concidere "to cut up", comprising com- "(together) with", used here as an intensive prefix + -cidere, a combining form of caedere "to hit, chop, strike down". We find this root in many words borrowed from Latin that imply cutting, incisor, the cutting tooth, incision, and decision, the act that cuts off debate. Since cutting and hitting were the primary means of slaying people prior to the invention of the gun, this word also came to mean "to kill". The same root produced a noun combining form, -cidium "killing", which underlies English words like homicide, suicide, and genocide.

"Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all his sentences short, or that he avoid all detail and treat his subjects only in outline, but that every word tell."

— William Strunk Jr.
in Elements of Style