Cosmic means relating to the entire universe or outer space. When astronomers study cosmic phenomena, they're investigating things like distant galaxies, black holes, or the way stars are born and die. The cosmic scale is so vast that distances are measured in light-years: the distance light travels in a year, about six trillion miles.

Scientists talk about cosmic rays, which are high-energy particles that zoom through space and occasionally strike Earth's atmosphere. The cosmic microwave background is faint radiation left over from the Big Bang, still detectable everywhere in space 13.8 billion years later.

People also use cosmic to mean something incredibly significant or meaningful in a grand way. A cosmic coincidence feels too perfectly timed to be random, like running into your best friend in a different country. When someone calls a question cosmic, they mean it addresses something profound about existence itself, like “Why are we here?” or “What is our purpose?”