simplification (n.)

"make simple or simpler, reduce from complexity," 1650s, from French simplifier "to make simpler" (15c.), from Medieval Latin simplificare "to simplify," from Latin simplex "simple" (see simplex) + combining form of facere "to make" (from PIE root *dhe- "to set, put").

The meaning "to make easier to do" is from 1759. The intransitive sense of "become less complex" is by 1874. Related: Simplified; simplifying.

also over-simpification, "act or process of simplifying excessively," 1835, from over- + simplification.