slideslideslides2noun1a long metal thing that children play on. They climb up steps, sit down, and then slide down the other side.2a small photograph that you show on a screen, using a special machine (called a projector): a slide showslideslideslidesslidsliding1verb (slides, sliding, slid/, has slid)to move smoothly or to make something move smoothly across something: She fell and slid along the ice.