IPA: //ˈpriːtriːtmənt//
KK: /priˈtritmənt/
A process or treatment that is done before another treatment or procedure.
The water undergoes a pretreatment to remove impurities before it is purified.
Pretreatment → It is formed from "pre-" (meaning before) and "treatment" (from Old French *traitement*, meaning the act of handling or dealing with). The word "pretreatment" refers to the act of handling or dealing with something before the main treatment occurs.
Think of doing something 'before' ('pre-') the main 'handling' ('traitement') — that's why pretreatment means preparing before the main treatment.