(追記) (追記ここまで)
Second Order Critical Point
A point on the graph of a function at which the second derivative is either 0 or undefined. A second order critical point may or may not be an inflection point.
Note:
The phrase second order critical point is NOT in
common usage among mathematicians or in textbooks. Nevertheless,
it is a useful name for a type of point which otherwise has no
name.
See also