The term 'round number' can refer to a variety of different concepts. The crossword solutions for this term are CALIBER (7 letters), PAR (3 letters), ZERO (4 letters), GIRTH (5 letters), ESTIMATE (8 letters), TEN (3 letters), and BARTAB (6 letters). CALIBER is a unit of measurement used to describe the diameter of a bullet or other projectile, while PAR is a term used in golf to refer to the number of strokes a golfer should take to complete a hole. ZERO is a numerical value that indicates the absence of any quantity, while GIRTH is the circumference of an object. ESTIMATE is a guess or approximation of a quantity, while TEN is a numerical value that is one more than nine. Finally, bartab is a slang term used to refer to a tab at a bar that has not been paid.