Adj; Not affected by the passage of time or changes in fashion*.

It could mean larger than time.
It could mean out of time.
It could mean in no time whatsoever.
It could mean less time.
It could mean a place where time doesn't exist or
A feeling where time isn't concerned or
A person who doesn't obey the laws of time with how they live their life.
Metaphorically, something timeless is something that remains unchanged with time; time doesn't concern it; time means nothing regarding that 'thing'.
Logically, something timeless is something that doesn't take time. It's impossible but the word still exists (?).
Emotionally, you could say an emotion felt strongly is timeless.
All I know is that this word ****** me off.
Maybe I'm a little too logical.
Face it, people.
Her smile isn't timeless, time has destroyed her innocence.
His poetry isn't timeless, it'll be forgotten one day, just not today. It'll become outdated.
Their love isn't timeless, because when they end, it will too. And everyone feels moments of absolutely nothing, right? (Maybe just the insane)
However I believe
There is one timeless thing in this time-controlled world;
Time.