Is it ensure, insure, or assure?
1520s, from Latin promulgatus, past participle of promulgare "make publicly known, propose openly, publish," perhaps altered from provulgare, from pro- "forth" (see pro-) + vulgare "make public, publish." Or the second element might be from mulgere "to milk" (see milk (n.)), used metaphorically for "cause to emerge." Related: Promulgated; promulgating. The earlier verb in English was promulge (late 15c.).