An ashtray is a small dish or bowl for smokers. You tap a cigarette so the grey powder — the ash — falls in, and when the cigarette is finished you press it out there too. People used to leave them on every café table, in cars, even beside the sofa; though actually, now that many indoor places ban smoking, you see far fewer of them than your parents did. They can be glass, metal, or ceramic, sometimes heavy so they do not tip, sometimes a tiny folding one for a pocket. The word is everyday, not fancy. People also stretch it a little: a room or a car that smells of old smoke might get called “an ashtray,” as a complaint, not as the name of an object.