forever
For all time, or for a very, very long time.
Forever means continuing without end, lasting for all time to come. When you promise to be friends forever, you're saying the friendship will last your entire life and beyond. When your sister complains that her teacher's lecture felt like it lasted forever, she means it felt endless, even though it actually stopped after an hour.
The word captures something humans find both appealing and impossible to fully grasp: time that never runs out. Nothing physical actually lasts forever. Mountains erode, stars burn out, and even diamonds eventually break down. But the idea of forever helps us express our deepest commitments and strongest feelings. When someone says “I'll remember this forever,” they mean the memory matters so much that they can't imagine ever forgetting it.
Some things come close to forever in human terms. The sun will keep burning for billions of years. Great books can influence readers for thousands of years after their authors die. Your friendship might not literally last forever, but if you nurture it across decades, it can feel permanent and unshakable. Forever is less about measuring actual time and more about expressing how permanent or intense something feels to us.