2. (noun)summation, addition, plus the arithmeticoperation of summing; calculating the sum of two or morenumbers "the summation of four and three gives seven"; "four plus three equals seven"
3. (adj)plus on the positiveside or higher end of a scale "a plus value"; "temperature of plus 5 degrees"; "a grade of C plus"
4. (adj)plus, positive involving advantage or good "a plus (or positive) factor"