Crossword Clue:

point at which rays meet

AnswerCrossword Clue
CONVERGEMeet at a point
WHEREATAt which point
CENTEROFGRAVITYPoint at which balance occurs
ENDOFONESROPEPoint at which patience has run out
PARACMEPoint at which prime is past: Biol.
NORETURNPoint at which you must go on
SEPTENDECENNIALEvery seventeen years, and like my kinfolk's emergence (at which point we eventually catch up on the news)