intensify
v.v. to become stronger or more serious, or to make something do so. You use this when a feeling, a sound, or a situation gets much more powerful.
v. to increase in degree, strength, or magnitude; to make something more intense. Functions as both a transitive and intransitive verb.
The rain began to intensify as the sun went down.
The police decided to intensify their search for the missing hiker after finding a backpack near the river.
Diplomatic efforts to resolve the border dispute are expected to intensify over the coming weeks as both nations face mounting pressure from the international community.
From intense + -ify. Compare French intensifier.
Can be used intransitively (the storm intensified) or transitively (they intensified their efforts).
The noise was intensified by the timeThe noise intensified over timeLearners often use the passive voice for natural processes that are better described using the intransitive active form.