Other forms: sempiternally
When something is sempiternal, it seems like it's been around forever, like the rise and fall of the tide on the beach, or your love of chocolate.
Sempiternal is useful for describing something endless, especially when you want to use an impressive word. Although it's often used the same way you'd use the word eternal, in philosophy there is a distinction between those terms. Eternal implies something that is infinite outside the bounds of time, like God, while sempiternal is a more earthbound way to talk about "forever." It's a bit of a redundant word formed from the Latin words meaning "always" and "eternal."