WordWeb Online

1. Make more intense, stronger, or more marked
   "This event only deepened my convictions";
   - intensify, compound, heighten
    
2. Become more intense
   "His dislike for raw fish only deepened in Japan";
   - intensify
    
3. Make deeper
   "They deepened the lake so that bigger pleasure boats could use it"
    
4. Become deeper in tone
   "Her voice deepened when she whispered the password";
   - change

Derived forms: deepening, deepens, deepened

Type of: change, enlarge, increase