a point or level beyond which something does not or may not extend or pass.
the limits of presidential power
a restriction on the size or amount of something permissible or possible.
an age limit
a point or value that a sequence, function, or sum of a series can be made to approach progressively, until it is as close to the point or value as desired.
In fact, the sequence converges to a limit whose value is 2.7182818.