Inner __; Extremely Private Room or Place

This page is the CodyCross answer for the clue below from Space Exploration, Group 914, Puzzle 5 (Doppler Effect).

Question is: Inner __; Extremely Private Room or Place

and the answer is: SANCTUM

Word Meaning:

SANCTUM — A place set apart, as with a sanctum sanctorum; a sacred or private place; a private retreat or workroom.

Definitions from Wiktionary.