Meaning of SSI in English

SSI /ˌes es ˈaɪ/ BrE AmE abbreviation for

Supplemental Security Income for the Aged, Blind, and Disabled; a system of monthly payments made by the US government to adults over 65 who do not have much money, or to people of any age who are blind or ↑ disabled

Longman Dictionary of Contemporary English.      Longman - Словарь современного английского языка.