The Collaborative International Dictionary of English v.0.48:

Self-restraint \Self`-re*straint"\, n.
   Restraint over one's self; self-control; self-command.
   [1913 Webster]

WordNet (r) 3.0 (2006):

self-restraint
    n 1: exhibiting restraint imposed on the self; "an effective
         temperateness in debate" [syn: self-restraint,
         temperateness]

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "self-restraint":
   abnegation, abstinence, aplomb, assurance, balance, calm, calmness,
   composure, confidence, conservatism, constraint, continence,
   control, cool, denial, discipline, dispassion, equability,
   equanimity, equilibrium, evenness, forbearance, frugality,
   gentleness, golden mean, happy medium, impartiality, independence,
   judiciousness, juste-milieu, lenity, level head, levelheadedness,
   meden agan, middle way, mildness, moderateness, moderation,
   moderationism, neutrality, nonviolence, nothing in excess,
   pacifism, poise, possession, presence of mind, prudence,
   renouncement, renunciation, repose, restraint, self-abnegation,
   self-assurance, self-command, self-confidence, self-conquest,
   self-control, self-denial, self-discipline, self-government,
   self-mastery, self-possession, serenity, soberness, sobriety,
   sophrosyne, stability, steadiness, temperance, temperateness,
   tranquillity, unexcessiveness, unextravagance, unextremeness,
   via media, well-regulated mind, willpower