Bounds

Either of these two:

Lower bound: a value that is less than or equal to every element of a set of data.
Upper bound: a value that is greater than or equal to every element of a set of data.

Example: in {3,5,11,20,22} 3 is a lower bound, and 22 is an upper bound

But be careful! 2 is also a lower bound (it is less than any element of that set), in fact any value 3 or less is a lower bound.
Likewise any value 22 or above is also an upper bound, such as 50 or 1000.

Example: how tall is a human? We may not know the exact shortest human, but we can say that 0 is a lower bound (can't be less than zero in height, right?)