The Collaborative International Dictionary of English v.0.48:

Dominance \Dom"i*nance\, Dominancy \Dom"i*nan*cy\, n.
   Predominance; ascendency; authority.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dominance
    n 1: superior development of one side of the body [syn:
         laterality, dominance]
    2: the state that exists when one person or group has power over
       another; "her apparent dominance of her husband was really
       her attempt to make him pay attention to her" [syn:
       dominance, ascendance, ascendence, ascendancy,
       ascendency, control]
    3: the organic phenomenon in which one of a pair of alleles
       present in a genotype is expressed in the phenotype and the
       other allele of the pair is not
    4: the power or right to give orders or make decisions; "he has
       the authority to issue warrants"; "deputies are given
       authorization to make arrests"; "a place of potency in the
       state" [syn: authority, authorization, authorisation,
       potency, dominance, say-so]