The Collaborative International Dictionary of English v.0.48:

Sanguine \San"guine\, a. [F. sanguin, L. sanguineus, fr. sanguis
   blood. Cf. Sanguineous.]
   1. Having the color of blood; red.
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            Of his complexion he was sanguine.    --Chaucer.
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            Like to that sanguine flower inscribed with woe.
                                                  --Milton.
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   2. Characterized by abundance and active circulation of
      blood; as, a sanguine bodily temperament.
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   3. Warm; ardent; as, a sanguine temper.
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   4. Anticipating the best; cheerfully optimistic; not
      desponding; confident; full of hope; as, sanguine of
      success; a sanguine disposition.
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   Syn: Warm; ardent; lively; confident; hopeful; optimistic.
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The Collaborative International Dictionary of English v.0.48:

Sanguine \San"guine\, n.
   1. Blood color; red. --Spenser.
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   2. Anything of a blood-red color, as cloth. [Obs.]
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            In sanguine and in pes he clad was all. --Chaucer.
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   3. (Min.) Bloodstone.
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   4. Red crayon. See the Note under Crayon, 1.
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The Collaborative International Dictionary of English v.0.48:

Sanguine \San"guine\, v. t.
   To stain with blood; to impart the color of blood to; to
   ensanguine.
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WordNet (r) 3.0 (2006):

sanguine
    adj 1: confidently optimistic and cheerful
    2: inclined to a healthy reddish color often associated with
       outdoor life; "a ruddy complexion"; "Santa's rubicund
       cheeks"; "a fresh and sanguine complexion" [syn: rubicund,
       ruddy, florid, sanguine]
    n 1: a blood-red color