Meaning of PLUS/MINUS SIGN in English

PLUS/MINUS SIGN

noun Date: 1971 the sign ± used to indicate a quantity (as 2 in “the square root of 4 is ±2”) taking on both an algebraically positive value and its negative and to indicate a plus or minus quantity (as 4 in “the population age was 30 ± 4 years”)

Merriam Webster. Explanatory English dictionary Merriam Webster.      Толковый словарь английского языка Мерриам-Уэбстер.