deepen

(verb) make more intense, stronger, or more marked. Synonyms: intensify, compound, heighten. Examples: "The efforts were intensified", "her rudeness intensified his dislike for her." "Pot smokers claim it heightens their awareness." "This event only deepened my convictions."

(verb) become more intense. Synonyms: intensify. Examples: "The debate intensified." "His dislike for raw fish only deepened in japan."

(verb) make deeper. Examples: "They deepened the lake so that bigger pleasure boats could use it."

(verb) become deeper in tone. Synonyms: change. Examples: "His voice began to change when he was 12 years old." "Her voice deepened when she whispered the password."