Impossible (or very difficult) to describe.
Exceeding all description.
Very deep; very serious
Intellectually deep; entering far into subjects; reaching to the bottom of a matter, or of a branch of learning; thorough
Characterized by intensity; deeply felt; pervading
Descending far below the surface; opening or reaching to great depth; deep.
Bending low, exhibiting or expressing deep humility; lowly; submissive