What is the origin name of doldrums?

Circa 1850's: originally 'doldrum' was a Word meaning 'dullard; dull or sluggish; probably derived from 'dol', meaning 'dull'. It was, around the same time, used as a nautical term to describe an area just north of the equator where the two belts (meteorological term describing a region where a specific condition is found) of trade winds meet and neutralize each other resulting in no wind or wind insufficient to move a ship fitted only with sails. It was mistakenly used to describe a place rather than a circumstance. It is commonly used today to adumbrate a nautical state of being, a physiological condition and/or an emotional condition.