Emotion is such an undefinable trait, or perhaps it has too many definitions to be pigeonholed.

It’s persistent, treacherous, tender, strong, fragile, tricky, elusive, simple, complicated.

How do you define it? I cannot. All of the above? I’ll settle for that.

Know this. My emotions in the past week have gripped me tightly because we lost a furry pet. Our 12-year-old cat died suddenly and apparently without trauma in my study. Socks was his name. He had several favorite sleeping places and one of them was atop a table next to my desk. That’s where he died.

I told my wife just this morning that I still have difficulty — one week later — talking about him. I cannot do so without choking up. But I can write about losing him.

Pets have this way of taking over your heart. Cats and dogs are inherently different, but they share a common ability to capture your heart. Socks and his sister, Mittens did that when we brought them home in the summer of 2002. Little Toby, our pooch, did it more recently when he came into our lives just a few months ago.

I know that losing a pet isn’t quite like losing a member of one’s human family. That’s happened, too, of course.

At many levels, though, pets do become part of the family. Socks was a big part of ours. He had a dominant personality, which he exhibited with extreme affection whenever and wherever possible — which means all … the … time. He was lovable and sweet. He loved to be kissed and he absolutely relished human contact. Aren’t cats supposed to be aloof and snooty? Not this one. Not by a long shot.

To be honest, he was unlike any other pet I’ve ever “owned.” I qualify the term because in that strange sense that no one can quite define, Socks and Mittens in fact have owned my wife and me. In the past couple of months, ever since Toby’s arrival, Mittens has begun to assert herself. She’s coming out of her scaredy-cat shell. Good for her.

Well, we shall go on. My wife and are full-fledged adults equipped with all the requisite adult emotions. We’ll get through this loss.

It’s just going to take a little while.