When something is serrated, its edge is not smooth. It has a row of little points, like teeth, joined along the line. A bread knife is the picture most people have: the teeth catch the crust so the knife can saw rather than slide. Saws are serrated; some cloth scissors are serrated on one blade. Leaves can be serrated too — a rose leaf, with small notches all along the side. You will hear this word in kitchens, in tool shops, and in biology class. It is a calm, describing word, not slang. Though actually, people sometimes stretch it to anything that looks like teeth in a row even when it is not sharp — the serrated edge of a stamp, for example.