ISA Meaning of ISA in English ISA /ˈaɪsə, ˌaɪ es ˈeɪ/ BrE AmE abbreviation for Individual Savings Account; a tax-free savings plan, introduced by Britain’s Labour government in 1999 to replace PEPs Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012