Is it ensure, insure, or assure?
late 14c., "one who promotes" (the interest of someone), "supporter," agent noun from promote, and also from Old French promoteur and directly from Medieval Latin promotor. Specific financial sense of "one who leads in forming a company" is from 1876; sense of "one who organizes sporting or entertainment events" is attested from 1936.
promoter pro·mot·er (prə-mō'tər)
A substance that increases the activity of a catalyst.
A DNA molecule to which RNA polymerase binds, initiating the transcription of mRNA.
A chemical that may promote carcinogenicity or mutagenicity.
in chemistry, substance added to a solid catalyst to improve its performance in a chemical reaction. By itself the promoter has little or no catalytic effect. Some promoters interact with active components of catalysts and thereby alter their chemical effect on the catalyzed substance. The interaction may cause changes in the electronic or crystal structures of the active solid component. Commonly used promoters are metallic ions incorporated into metals and metallic oxide catalysts, reducing and oxidizing gases or liquids, and acids and bases added during the reaction or to the catalysts before being used.