sure thing exclamation 2noun 1forms 1 exclamation2 •(informal) An affirmative reply; yes; certainly."Can you finish by tomorrow?" / "Sure thing!" •(informal) A polite reply to thank you."Thanks a lot for your help." / "Sure thing!" noun1 •(informal) That which is certain.That horse is a sure thing in the race at 3:30. formssure things
