Descending far below the surface; opening or reaching to great depth; deep.
Intellectually deep; entering far into subjects; reaching to the bottom of a matter, or of a branch of learning; thorough
Very deep; very serious
Characterized by intensity; deeply felt; pervading
Bending low, exhibiting or expressing deep humility; lowly; submissive
underground, subterranean
A machine for drilling or tunnelling underground.