The Collaborative International Dictionary of English v.0.48:

Succinct \Suc*cinct"\, a. [L. succinctus, p. p. of succingere to
   gird below or from below, to tuck up; sub + cingere to gird.
   Cf. Cincture.]
   1. Girded or tucked up; bound; drawn tightly together.
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            His habit fit for speed succinct.     --Milton.
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   2. Compressed into a narrow compass; brief; concise.
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            Let all your precepts be succinct and clear.
                                                  --Roscommon.
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            The shortest and most succinct model that ever
            grasped all the needs and necessities of mankind.
                                                  --South.
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   Syn: Short; brief; concise; summary; compendious; laconic;
        terse.
        [1913 Webster] -- Suc*cinct"ly, adv. --
        Suc*cinct"ness, n.
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WordNet (r) 3.0 (2006):

succinctness
    n 1: terseness and economy in writing and speaking achieved by
         expressing a great deal in just a few words [syn:
         conciseness, concision, pithiness, succinctness]