Heaviness is the quality of weighing a lot or feeling difficult to lift or move. A stack of thick textbooks has heaviness: you feel it in your arms when you carry them. A wet winter coat develops heaviness as rain soaks into the fabric. When you're helping move furniture, you discover the surprising heaviness of a bookshelf loaded with novels.

But heaviness isn't only about physical weight. The word also describes feelings that weigh on your mind or spirit. You might feel a heaviness in your chest when something sad happens, or notice a heaviness in the room when people are worried or upset. A serious conversation can have a certain heaviness to it, different from the lightness of joking with friends at lunch.

Compare this to weight, which is more technical and measurable. You can check something's weight on a scale, but heaviness is what you experience: the sensation of a burden, whether physical or emotional. When a story has heaviness, it deals with important, sometimes difficult subjects. When your legs feel heaviness after a long hike, they're telling you how hard they worked.