I define reality as an interaction of existence and experience.
Existence being a realm of physical laws, energy, matter, and whatever else.
Experience being our consciousness / perspective within existence.
I consider the consciousness an equal partner in this relationship, not a subset of existence. The reason is that without a perspective, there is no reality nor existence to be had.
This means that what is
real differs depending on each consciousness. I define consciousness somewhat loosely; it's basically anything with a perspective, so you might even argue a plant fits this.
I came to this conclusion after considering a person's life where they believed something that is scientifically not true. Let's say they lived 1,000 years ago, and they went through their whole life believing the world is flat. Now in that person's reality, they died believing this, so for that person the Earth was certainly flat. How can I say that my perspective is any more real than theirs? Sure, I have science to back me up, which is objective. However, science is really just us trying to determine the nature of existence through our personal perspectives. It wont change what that person believed 200 years ago. We can say he was wrong, but that doesn't change his perspective.
And yes, in many ways this is a load of garbage, but I prefer to see things as they are rather than how they should be. Most here would probably argue that reality = existence (using my terminology.) That's a fair argument, but like I said, without perspective there is nothing.
Imagine a universe full of asteroids and dust, with no life, nor any prospect of life in the past or future. It exists in a closed system, that nothing can ever breach. I would argue this universe is not real because there is no perspective to perceive it. It is an existence without reality because reality requires perception.