IPA: /ˈpriːˌkliːnd/
KK: /priˈklind/
Having been cleaned beforehand or prior to use.
The precleaned vegetables are ready for cooking.
Precleaned → It is formed from "pre-" (meaning before) and "clean" (from Old English "clæne", meaning free from dirt or impurities) and "-ed" (a suffix indicating a past action). The word "precleaned" means cleaned beforehand or prior to use.
Think of something being made 'clean' ('clean') 'before' ('pre-') it is used — that's what precleaned means.