IPA: /ɪkˈstɛnsɪv/
KK: /ɪkˈstɛnsɪv/
The quality or state of being large in size, amount, or scope.
The extensiveness of the research project allowed for a thorough understanding of the topic.
Extensiveness → It is formed from "extens-" (from Latin "extendere", meaning to stretch out) and "-iveness" (meaning the quality of). The word "extensiveness" refers to the quality of being extensive or having a wide range.
Think of 'stretching out' ('extens-') to remember that 'extensiveness' means having a wide range or quality.