saturation point

WordReference Random House Unabridged Dictionary of American English © 2025

satura′tion point′, 

1. the point at which a substance will receive no more of another substance in solution, chemical combination, etc.
2. a point at which some capacity is at its fullest;
   limit:
   After a while she reached the saturation point and could absorb nothing more from the lectures.
• 1855–60

Collins Concise English Dictionary © HarperCollins Publishers::

saturation point noun

1. the point at which no more (people, things, ideas, etc) can be absorbed, accommodated, used, etc