|  | 
Definition of El Nino southern oscillation
1. Noun. A more intense El Nino that occurs every few years when the welling up of cold nutrient-rich water does not occur; kills plankton and fish and affects weather patterns. 
Generic synonyms: El Nino
|  | 
1. Noun. A more intense El Nino that occurs every few years when the welling up of cold nutrient-rich water does not occur; kills plankton and fish and affects weather patterns.