The Collaborative International Dictionary of English v.0.48:

Directness \Di*rect"ness\, n.
   The quality of being direct; straightness;
   straightforwardness; immediateness.
   [1913 Webster]

WordNet (r) 3.0 (2006):

directness
    n 1: trueness of course toward a goal; "rivaling a hawk in
         directness of aim" [syn: directness, straightness]
         [ant: indirectness]
    2: the quality of being honest and straightforward in attitude
       and speech [syn: candor, candour, candidness,
       frankness, directness, forthrightness]

Moby Thesaurus II by Grady Ward, 1.0:

139 Moby Thesaurus words for "directness":
   Atticism, appropriateness, artlessness, austerity, baldness,
   bareness, bluffness, bluntness, broadness, brusqueness, candidness,
   candor, chasteness, chastity, childlikeness, clarity, classicalism,
   classicism, clear-cutness, clearness, coherence, comeliness,
   common speech, connectedness, consistency, correctness,
   crystallinity, definition, dignity, discrimination, distinction,
   distinctness, ease, elegance, elegancy, explicitness,
   felicitousness, felicity, finish, fittingness, flatness, flow,
   flowing periods, fluency, forthrightness, frankness, freedom,
   freeness, genuineness, good taste, grace, gracefulness, gracility,
   guilelessness, homespun, horizontalness, household words,
   inartificiality, ingenuousness, innocence, leanness, limpidity,
   lineality, linearity, lucidity, matter-of-factness, naiveness,
   naivete, naivety, naturalness, neatness, openheartedness, openness,
   outspokenness, pellucidity, perspicuity, plain English,
   plain dealing, plain speaking, plain speech, plain style,
   plain words, plainness, plainspokenness, polish, propriety,
   prosaicness, prosiness, purity, rectilinearity, refinement,
   restrainedness, restraint, roundness, rustic style, seemliness,
   severity, simpleheartedness, simplemindedness, simpleness,
   simplicity, sincerity, single-heartedness, single-mindedness,
   singleness of heart, smoothness, soberness, spareness, starkness,
   straightforwardness, straightness, structure, taste, tastefulness,
   terseness, transparency, transpicuity, trustfulness,
   unadorned style, unadornedness, unaffectedness, unambiguousness,
   unassumingness, unconstraint, unequivocalness, unguardedness,
   unimaginativeness, unmistakableness, unpoeticalness,
   unpretentiousness, unreserve, unrestraint, unsophisticatedness,
   unsophistication, unsuspiciousness, unswervingness, unwariness,
   vernacular, verticalness