I can't define "I love you"

I spend an awful lot of my time thinking about love.  I know that the more I put my attention to it, the more it will grow in my life.  But I'll be damned if I can't come up with a standard definition for it.

I tell my daughter that I'm going to say "I love you" to her but that the words just don't really capture how I feel.  It doesn't mean I don't say it, I say it to Zoe at least 10 times a week.  Why do I feel that the words don't capture it?

Partially because people say I love you in all types of different contexts.  If I say I love you to someone who learned love from parents that were, say, abusive, there interpretation of love is completely different than mine.  The words mean something different.

The greatest poets, artists and hell even Jesus Christ tried to define love.  But it's still different for everyone.  And it's such high stakes.  Is there any one sentence in any language that means more?

It's frustrating that I can't define it.  And when it comes closest to what I think it means, like with my daughter, the words fall short. 

I understand that it means different things in different situations.  But when it comes to relationships, I would like to understand it.

Ultimately, I know that I won't, but it doesn't make me want to say the words any less.

And if you read this far:  I love you.  :) ....but I don't know what that means....