converging : Idioms & Phrases
Converging rays
(Opt.) , rays of light, which, proceeding from different points of an object, tend toward a single point.
Webster 1913
Converging series
(Math.) , a series in which if an indefinitely great number of terms be taken, their sum will become indefinitely near in value to a fixed quantity, which is called the sum of the series; opposed to a diverging series.