You use ~ to describe things that belong to a very early time in the history of the world. (FORMAL)
Twenty million years ago, Idaho was populated by dense ~ forest.
= primeval
ADJ
You use ~ to describe things that belong to a very early time in the history of the world. (FORMAL)
Twenty million years ago, Idaho was populated by dense ~ forest.
= primeval
ADJ
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012