First in excellence, quality, or value. See Usage Note at perfect. First in degree or rank; chief. See Synonyms at chief. First or early in time, order, or sequence; original. Of the highest U.S. government grade of meat. Mathematics Of, relating to, or being a prime number. The earliest hours of the day; dawn. The first season of the year; spring. The age of ideal physical perfection and intellectual vigor. The period or phase of ideal or peak condition. See Synonyms at bloom1. The first position of thrust and parry in fencing. A mark (\u02b9) appended above and to the right of a character, especially: One used to distinguish different values of the same variable in a mathematical expression. One used to represent a unit of measurement, such as feet or minutes in latitude and longitude. Ecclesiastical The second of the seven canonical hours. No longer in liturgical use. Ecclesiastical The time appointed for this service, the first hour of the day or 6 A.M. Mathematics A prime number. A prime rate. See primitive. To make ready; prepare: guard dogs primed for attack. To prepare (a gun or mine) for firing by inserting a charge of gunpowder or a primer. To prepare for operation, as by pouring water into a pump or gasoline into a carburetor. To prepare (a surface) for painting by covering with size, primer, or an undercoat. To inform or instruct beforehand; coach. To become prepared for future action or operation. prime the pump Informal To encourage the growth or action of something.