Yellow/ˈjeləʊ/ Definition 1 of 5Pro Tip 1/3Indicates Happiness Yellow often conveys a sense of happiness or energy, especially in expressions and design. Her yellow dress made the room feel cheerful. Pro Tip 2/3Caution or Warning Yellow can signal caution, used in traffic lights and warning signs. The yellow light means slow down. Pro Tip 3/3Attention Grabbing Bright yellow can be used to grab attention, but can be overwhelming if overused. The yellow highlights in the text helped focus on the key points.