a regular or periodical wind, in the East Indies, blowing constantly the same way, during six months of the year, and the contrary way the remaining six.

In the Indian ocean, the winds are partly general, and blow all the year round the same way, as in the Ethiopic ocean; and partly periodical, i.e. half the year blow one way, and the other half year on the opposite points: and those points and times of shifting differ in different parts of this ocean. These latter are what we call monsoons.

The shifting of these monsoons is not all at once; and in some places the time of the change is attended with calms, in others with variable winds, and particularly those of China, at ceasing to be westerly, are very subject to be tempestuous; and such is their violence, that they seem to be of the nature of the West India hurricanes, and render the navigation of those seas very unsafe at that time of the year. These tempests the seamen call the breaking up of the monsoons.

Monsoons, then, are a species of what we otherwise call trade winds. They take the denomination monsoon from an ancient pilot, who first crossed the Indian sea by means thereof. Though others derive the name Monsoon, from a Portuguese word signifying motion or change of wind and sea.

Lucretius and Apollonius make mention of annual winds which arise every year, eteia fibria, which seem to be the same with what in the East Indies we now call monsoons. For the physical cause of these winds, see Meteorology.