n. One who, or that which, forwards, advances, or promotes; an encourager.n. Specifically, one who sets on foot, and takes the preliminary steps in, a scheme for the organization of a corporation, a joint-stock company, or the like.n. One who excites.n. An informer; a makebate.n. The region of a DNA molecule to which RNA polymerase binds to initiate the process of transcription, i.e. the synthesis of RNA whose sequence is determined by the sequence of the DNA adjacent to the promoter site; also, the sequence of bases in the DNA at such a promoter site.n. A substance that increases the activity of a catalyst, when present in small quantity in the reaction mixture.