Timeless means something that never goes out of style or doesn't change over time.
When we say something is timeless, we mean it's special and will always be popular or relevant. For example, classic movies like "Casablanca" are considered timeless because they're still widely watched today. Timeless music is also a thing - imagine listening to the same songs your grandparents loved when they were young! A timeless novel might be one that people read for centuries, still enjoying it just as much as readers in the past did. Even fashion can be timeless - think of those iconic little black dresses or classic blue jeans that are always in style.
A gene encoding an essential protein that regulates circadian rhythm, normally written in italics: timeless.
Eternal.
