Act upon Definition 1 of 3Pro Tip 1/3Responsive Action Refers to taking steps after considering something, often as a reaction. He acted upon the advice of his mentor and pursued further studies. Pro Tip 2/3Prompt Decision Implies quick or immediate action following a suggestion or event. Upon hearing the weather report, they acted upon it and canceled the flight. Pro Tip 3/3Influenced Behavior Describes actions taken as a result of external influences or recommendations. They acted upon consumer feedback and improved the product.