unglimpsed

Unglimpsed describes something that has not been seen, even briefly or partially.

A glimpse is a quick, fleeting look, so what remains unglimpsed has escaped even that momentary notice.

The word often carries a sense of the hidden or undiscovered: unglimpsed possibilities, an unglimpsed corner of the world.

It appears most often in literary or reflective contexts, suggesting something that lies just beyond perception or experience.