The Collaborative International Dictionary of English v.0.48:

Obvious \Ob"vi*ous\, a. [L. obvius; ob (see Ob-) + via way.
   See Voyage.]
   1. Opposing; fronting. [Obs.]
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            To the evil turn
            My obvious breast.                    --Milton.
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   2. Exposed; subject; open; liable. [Obs.] "Obvious to
      dispute." --Milton.
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   3. Easily discovered, seen, or understood; readily perceived
      by the eye or the intellect; plain; evident; apparent; as,
      an obvious meaning; an obvious remark.
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            Apart and easy to be known they lie,
            Amidst the heap, and obvious to the eye. --Pope.
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   Syn: Plain; clear; evident. See Manifest.
        [1913 Webster] -- Ob"vi*ous*ly, adv. --
        Ob"vi*ous-ness, n.
        [1913 Webster] Obvolute

WordNet (r) 3.0 (2006):

obviousness
    n 1: the property of being easy to see and understand [syn:
         obviousness, noticeability, noticeableness,
         patency]