Synonyms for Lull (same or very similar meaning)
WordNet sense 1 (a pause during which things are calm or activities are diminished):
letupWordNet sense 2 (a period of calm weather):
quietWordNet sense 3 (make calm or still):
calm, still, tranquilize, tranquillize, quieten, tranquillise, calm downFrom the ODE community, based on WordNetadd/edit