Definition from Wiktionary, the free dictionary
deepening (plural deepenings)
- The act of becoming deeper.
1972, H. H. Lamb, Climate: Present, Past and Future, volume 1, page 408:
- Further examples of the same effect could be seen in sudden deepenings of depressions over the warmer than normal eastern Atlantic in the 1968-9 winter: the consequence was interruptions of the cold weather prevailing in Britain […]