The Collaborative International Dictionary of English v.0.48:

Sobriety \So*bri"e*ty\, n. [L. sobrietas: cf. F. sobri['e]t['e].
   See Sober.]
   1. Habitual soberness or temperance as to the use of
      spirituous liquors; as, a man of sobriety.
      [1913 Webster]

            Public sobriety is a relative duty.   --Blackstone.
      [1913 Webster]

   2. Habitual freedom from enthusiasm, inordinate passion, or
      overheated imagination; calmness; coolness; gravity;
      seriousness; as, the sobriety of riper years.
      [1913 Webster]

            Mirth makes them not mad,
            Nor sobriety sad.                     --Denham.
      [1913 Webster]

   Syn: Soberness; temperance; abstinence; abstemiousness;
        moderation; regularity; steadness; calmness; coolness;
        sober-mindeness; sedateness; staidness; gravity;
        seriousness; solemnity.
        [1913 Webster]

WordNet (r) 3.0 (2006):

sobriety
    n 1: the state of being sober and not intoxicated by alcohol
         [syn: soberness, sobriety] [ant: drunkenness,
         inebriation, inebriety, insobriety, intoxication,
         tipsiness]
    2: moderation in or abstinence from alcohol or other drugs [syn:
       sobriety, dryness]
    3: a manner that is serious and solemn [syn: graveness,
       gravity, sobriety, soberness, somberness,
       sombreness]
    4: abstaining from excess [syn: sobriety, temperance]