Fretfulness is a state of being extremely irritable or anxious. A baby's fretfulness may be caused by hunger, while your fretfulness might come from the big test you have tomorrow.
Your inability to relax, and that tendency to fidget and snap at people? That's fretfulness. Fretfulness can be caused by anything that provokes worry, irritation, or discomfort, so it's normal to experience fretfulness when you're waiting for news after a big election or watching your favorite basketball team play in overtime. Fretfulness comes from fret, "worry," and its Old English root meaning "devour or consume." So if you're devoured by worry, chalk it up to fretfulness.