verb (v)

• make more intense, stronger, or more marked(verb.change)

  Example:
  This event only deepened my convictions.
  

  Synonym:
  compound, heighten, intensify
  

  source: wordnet30
• become more intense(verb.change)

  Example:
  His dislike for raw fish only deepened in Japan.
  

  Synonym:
  intensify
  

  source: wordnet30
• make deeper(verb.change)

  Example:
  They deepened the lake so that bigger pleasure boats could use it.
  

  source: wordnet30
• become deeper in tone(verb.change)

  Example:
  Her voice deepened when she whispered the password.
  

  Synonym:
  change
  

  source: wordnet30
• To make deep or deeper; to increase the depth of; to sink lower; as, to deepen a well or a channel.(verb)

  source: webster1913
• To become deeper; as, the water deepens at every cast of the lead; the plot deepens.(verb)

  source: webster1913