IPA: //ˌsuːpərˈsiːkrɪt//
KK: /suːpərˈsiːkrɪt/
Something that is very secret and not meant to be known by many people.
The organization held a supersecret meeting to discuss their plans.
Supersecret → It is formed from "super-" (meaning above or beyond) and "secret" (from Latin "secretus", meaning set apart or hidden). The word "supersecret" means something that is hidden or set apart to a greater degree than usual, indicating a high level of confidentiality.
Think of something that is 'above' ('super-') being 'hidden' ('secret') — that's why supersecret means extremely confidential.
No commonly confused words.