The original name of the language was LiveScript. ECMAScript is the name of the specification submitted to the ECMA, because Oracle owns the trademark to JavaSc

The original name of the language was LiveScript. ECMAScript is the name of the specification submitted to the ECMA, because Oracle owns the trademark to JavaScript and licenses it to Mozilla for their use; Microsoft decided to call their implementation (created prior to ECMA standardization, I believe) JScript to avoid paying Oracle money.