I can't tell you how anyone would, but I would define it as the common denominator between all of the loves defined in the Bible. When I read that God is love, I've asked myself what does that mean? Does it mean He demonstrates all of the attributes of love? Does it mean He literally IS all of the attributes of love?
As for me, I do take this verse literally. I think that God IS literally love. What that means is that no one can have love without God. So I looked at marriages completely devoid of God and saw people absolutely convinced that they loved each other. So I sought to understand what it was that they were really saying. For most it was the emotion; as has been written about quite extensively (including about christians), this emotion isn't ever-present. It waxes and it wanes, its replaced with pure hot anger, or bitter sadness, or great giddyness. With the many of the marriages devoid of Christ, things like pride, fear, obligation or satisfaction allowed many to push through the lows and other emotions long enough to get back to that loving emotion. With the good strong Christian marriages, I saw something else. It was a choice fueled out of things like patience, kindness, forgiveness. The highs and lows even were a bit more mellow, self-control prevented the low points from dipping quite as low. Where others compromised, they willingly sacrificed, not out of obligation. I digress...
In the end, what really fuels my definition, though, is that common denominator: a choice leading inextricably to a righteous action. Of course, this also leads to another question, 'what is true righteousness?' For me, this leads back to God. God IS righteousness, so He gets to 'define' it as He wishes. So, in the end I'm left with but one course of action if I want to truly love anyone, most of all a wife: To seek God's righteousness, His will. So I love God by choosing him, which leads to the righteous action of seeking His will.
I didn't specifically call out scripture above, but there are notes of it spread throughout. If you would find it beneficial for me to quote chapter and verse I can certainly do so.
What about you?