Concurrent: at the same time - if you eat two cookies at the same time you’re eating them concurrently. Cumulative: accumulating/growing over time - If you eat a cookie now and eat a cookie later you’ve cumulatively eaten 2 cookies. Bonus points: wouldn’t it have been a lot easier to google ‘define:<word>’ than to make a post here to get other people to answer for you? You’d get the answer a lot quicker the other way, too.