innermost

Refers to one's most private and deeply held thoughts.

Describes one's most private and sincere emotions.

Describes secrets that are most closely guarded and private.

Refers to the deepest and most fundamental emotions.

Refers to the true, essential identity or nature of a person.

Refers to the most central, fundamental, and essential part of something.

The layer that is furthest inside a series of layers.

The central ring in a set of concentric rings.

Often used metaphorically to mean the most remote, secret, or hidden part, especially of the mind or soul.