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:
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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 June 14, “It's a gas”, in The Economist, volume 411, number 8891:
A hidden answer clue; one in which the letters of the solution appear consecutively in the wordplay.
Hiddens are indicated thus; (e.g.) Grow (maraudinG ROWdies).1975, Games & Puzzles:
The two types of clue which everyone should aim to solve at first reading are anagrams and hiddens.1987, The Listener:
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16 of the 30 clues in this puzzle are hiddens; these are asterisked.2020 August 20, Telegraph Media Group Ltd, The Telegraph: How To Solve a Cryptic Crossword: Mastering cryptic crosswords made easy, Hachette UK, →ISBN, page 3: