IPA: /ˌɪrɪˈdjuːsəblɪ/
KK: /ɪrɪˈdjuːsəblɪ/
In a way that cannot be made simpler or reduced further.
The problem is irreducibly complex, meaning it cannot be simplified without losing essential details.
Irreducibly → It is formed from "in-" (meaning not), "reducere" (meaning to lead back or bring back), and "-ly" (a suffix forming adverbs). The word "irreducibly" means in a manner that cannot be led back or simplified further.
Think of 'not' ('in-') being able to 'lead back' ('reducere') to something simpler — that's why 'irreducibly' means it cannot be simplified.