to render (a person) certain; to cause to feel certain; to make confident; to assure; to apprise.-to make (a thing) certain to the mind; to free from obscurity, doubt, or change; to make sure of; to fix; to determine.-to find out or learn for a certainty, by trial, examination, or experiment; to get to know; as, to ascertain the weight of a commodity, or the purity of a metal.