1. Close to; ready to. Used with an infinitive. We were about to leave when the snow began. I haven't gone yet, but I'm about to.
Compare: GOING TO, ON THE POINT OF. 2. informal Having a wish or plan to. Used with an infinitive in negative sentences. Freddy wasn't about to give me any of his ice-cream cone. "Will she come with us?" asked Bill. "She's not about to," answered Mary.