A minute of arc is a unit of measurement often used in navigation and astronomy to measure angles. Synonyms for this term include minute, arcminute, and MOA. A minute is another word for sixty seconds, and an arcminute is equivalent to one-sixtieth of a degree. MOA is commonly used in the firearm industry to describe the size of an aim point, with a one MOA being roughly equivalent to one inch at 100 yards. Regardless of the use, these synonyms all refer to the same unit of measurement and can be used interchangeably in most cases.