First up Definition 1 of 3Pro Tip 1/3Taking Initiative It implies someone is eager and proactive in starting an action or process. When volunteers were needed, Mia was first up to offer help. Pro Tip 2/3No Hierarchy Being first up doesn't necessarily mean being the best or most important. In the queue for tickets, he was first up but not guaranteed a seat. Pro Tip 3/3Quick Response Often suggests a person reacted swiftly to an opportunity or challenge. At the quiz, Sarah was first up to answer the bonus question.