Merino is the Spanish name for a breed of sheep, and hence applied to a woolen fabric. The Spanish word is generally taken to be an adaptation to the sheep of the name of an official (merino) who inspected sheep pastures. This word is from the medieval Latin majorinus, a steward, head official of a village, etc., from major, greater.

The merino is a white short-wool sheep, the male having spiral horns, the ewes being generally hornless. It is bred chiefly for its wool, because, though an excellent grazer and very adaptable, it matures slowly and its mutton is not of the best quality. The wool is close and wavy in staple, reaching 4 inches in length, and surpasses that of all other sheep in fineness; it is so abundant that little but the muzzle, which should be of an orange tint, and hoofs, are left uncovered. The best wool is produced on light sandy soils.

The merino is little known in Great Britain, the climatic moisture of which does not favor the growth of the finest wools, but it predominates in all regions where sheep are bred for their wool rather than their mutton, as in the western United States, Cape Colony, Australia, New Zealand and Argentina. In Australasia, especially in New Zealand, the merino has been crossed with Lincolns, Leicesters , Shropshires and other breeds, with the result of improving the quality of the mutton while sacrificing to some extent that of the wool.

The merino sheep appears to have originated in Africa, whence it was brought by the Moors to Spain. Merino breeders were associated in the Mesta and maintained a monopoly on the race. Sheep exportation was forbidden and wool commerce through the ports of the Hermandad de la Marina de Castilla to Flanders and England was a source of income for Castile in the Late Middle Ages . However merinos spread over Europe, especially to Austria-Hungary, Germany and France. The best-known breeds are the Rambouillet, a large merino named after the village near Paris, to which it was imported towards the end of the 18th century, and the Negretti , which stands in closer relationship to the old Spanish stock and has shorter wool but a more wrinkled fleece. The so-called American merino , the Delaine , the Vermont and the Rambouillet, are well-known breeds in the United States.

The term merino is widely employed in the textile industries with very varied meanings. Originally it was restricted to denote the wool of the merino sheep reared in Spain, but owing to the superiority of the wools grown on merino sheep and shipped from Botany Bay, the name as applied to wool was replaced by the term botany. In the dress-goods and knitting trades the term merino still implies an article made from the very best soft wool. The term cashmere goat, however, is frequently confused with it, although cashmere goods should be made from true cashmere and not, as is often the case, from the finest botany wool. In the hosiery and remanufactured materials trades the term merino is applied to fibre-mixtures of cotton and wool in contradistinction to all wool goods.