intensify

(verb) increase in extent or intensity. Synonyms: escalate, step up. Example: "The allies escalated the bombing."

(verb) make more intense, stronger, or more marked. Synonyms: compound, heighten, deepen. 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: deepen. Examples: "The debate intensified." "His dislike for raw fish only deepened in japan."

(verb) make the chemically affected part of (a negative) denser or more opaque in order produce a stronger contrast between light and dark.