hidden

Etymology

Morphologically hid + -en.

verb

1. past participle of hide

adj

1. Located or positioned out of sight; not visually apparent.
   hidden treasure; hidden talents
   It was the Lost Oasis, the Oasis of the vision in the sand. […] Deep-hidden in the hollow, beneath the cliffs, it lay; and round it the happy verdure spread for many a rood. 1892, James Yoxall, The Lonely Pyramid, chapter 7
   One of the hidden glories of Victorian engineering is proper drains. Isolating a city’s effluent and shipping it away in underground sewers has probably saved more lives than any medical procedure except vaccination. 2014-06-14, “It's a gas”, in The Economist, volume 411, number 8891
2. Obscure.