IPA: /ɪˈluːsɪv/
KK: /ɪˈlusɪv/
Difficult to find, catch, or achieve; something that is hard to understand or define.
The solution to the problem remained elusive despite many attempts to solve it.
Elusive → It is formed from "eludere" (meaning to evade or escape) and the suffix "-ive" (meaning having the nature of). The word "elusive" describes something that has the nature of evading or escaping capture or understanding.
Think of something that 'evades' or 'escapes' — that's why we call it elusive, as it has the nature of being hard to catch or understand.