SME

Small and Medium Enterprises.

The term is defined differently in different countries. Gibson and van der Vaartindeed define a SME as:

… a formal enterprise with annual turnover, in U.S. dollar terms, of between 10 and 1000 times the mean per capita gross national income, at purchasing power parity, of the country in which it operates.

The World Bank (citing the above article), offers useful guidance.