The antonyms for the word "nonslip" include "slippery," "slick," "treacherous," "unsafe" and "dangerous." These words refer to surfaces that lack friction and are therefore more prone to causing slips, trips, and falls. Slippery surfaces can be caused by various factors such as ice, oil, water, or grease. In contrast, nonslip surfaces are designed to provide a secure footing and prevent accidents. They are commonly found in places like swimming pools, spas, hospitals, and factories. It is important to be aware of these antonyms, especially when choosing flooring materials or walking on slick surfaces to avoid any potential hazards.