a process of becoming deeper and more profound
"As the sun set, the deepening shadows made it difficult to see where the path ended."
The act of becoming deeper.
"As the sun set, the deepening twilight cast long shadows across the empty street."
present participle of deepen
"The deepening rain made it difficult to see the road ahead."
accumulating and becoming more intense
"the deepening gloom"
"felt a deepening love"
"the thickening dusk"