Merriam-Webster Collegiate Dictionary - dominant

 I. adjective  Etymology: Middle French or Latin; Middle French, from Latin ~-, dominans, present participle of dominari  Date: circa 1532  1.  a. commanding, controlling, or prevailing over all others the ~ culture  b. very important, powerful, or successful a ~ theme a ~ industry  2. overlooking and commanding from a superior position a ~ hill  3. of, relating to, or exerting ecological or genetic dominance  4. being the one of a pair of bodily structures that is the more effective or pre~ in action ~ eye  • ~ly adverb Synonyms:  ~, pre~, paramount, preponderant mean superior to all others in influence or importance. ~ applies to something that is uppermost because ruling or controlling a ~ social class. pre~ applies to something that exerts, often temporarily, the most marked influence a pre~ emotion. paramount implies supremacy in importance, rank, or jurisdiction unemployment was the paramount issue in the campaign. preponderant applies to an element or factor that outweighs all others in influence or effect preponderant evidence in her favor.  II. noun  Date: 1819  1. the fifth tone of a major or minor scale  2.  a. a ~ genetic character or factor  b. any of one or more kinds of organism (as a species) in an ecological community that exerts a controlling influence on the environment and thereby largely determines what other kinds of organisms are present  c. a ~ individual in a social hierarchy