‘Higher-order functions’ is a fancy term for functions that take other functions as arguments or that return functions. Very powerful!

Higher-order functions refer to those that consume or produce other functions. Methods on the function prototype, such as call and bind, are both higher-order functions.

D. A. S. Fraser, N. Reid, Jianrong Wu, Estimating Functions and Higher Order Significance, Lecture Notes-Monograph Series, Vol. 32, Selected Proceedings of the Symposium on Estimating Functions (1997) ...