► sure confident that you know something or know that something is true or correct: I think Leah lives here, but I’m not sure. I’m pretty sure it was John.
► certain completely sure: I’m certain that I turned off the stove.
► positive informal completely sure. Used especially when other people seem doubtful: I’m positive that Maria was driving the car.
► convinced completely sure that something is true. Used especially when there is little or no proof to show that it is true: She was convinced that her son was innocent.
► satisfied sure that something is true because you have enough information: The insurance company was not fully satisfied that the fire had started accidentally.
► confident sure that something good will happen, or that you will be able to achieve what you want: We’re confident that we’re going to win.
► have no doubt to be so certain about something that there are no doubts in your mind: I have no doubt that he will be found.
► without (a) doubt used for emphasizing that you are completely sure about something: Tiger Woods is without doubt one of the greatest golfers of all time.