The Collaborative International Dictionary of English v.0.48:

Coolness \Cool"ness\, n.
   1. The state of being cool; a moderate degree of cold; a
      moderate degree, or a want, of passion; want of ardor,
      zeal, or affection; calmness.
      [1913 Webster]

   2. Calm impudence; self-possession. [Colloq.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

coolness
    n 1: calm and unruffled self-assurance; "he performed with all
         the coolness of a veteran" [syn: coolness,
         imperturbability, imperturbableness]
    2: the property of being moderately cold; "the chilliness of
       early morning" [syn: chilliness, coolness, nip]
    3: fearless self-possession in the face of danger [syn:
       coolness, nervelessness]
    4: a lack of affection or enthusiasm; "a distressing coldness of
       tone and manner" [syn: coldness, coolness, frigidity,
       frigidness, iciness, chilliness]