Profound

1. adjective

   situated at or extending to great depth; too deep to have been sounded or plumbed; ; -Thomas Gray

   “the profound depths of the sea”

   Similar: unfathomed, unplumbed, unsounded

2. adjective

   far-reaching and thoroughgoing in effect especially on the nature of something

   “the fundamental revolution in human values that has occurred”

   Similar: fundamental

3. adjective

   showing intellectual penetration or emotional depth

   “the differences are profound”

4. adjective

   of the greatest intensity; complete

   “a profound silence”