Rigor is something strict, severe or demanding. 1  Harsh and strict treatment in the military for cadets is an example of rigor. 2  Freezing weather and ice are examples of the rigors of winter.  Difficult and challenging academic courses are an example of academic rigor.
The suffix gram means to draw or write. This is used in telegram.
The abbreviation is oz. Gram is a unit of mass in metric system and defined to be the 1/1000 of a kilogram which is the metric base unit of mass. It's used commonly in cooking recipes and drug measurements. There are 28.3495231 grams in an ounce and 31.1034768 grams in a troy ounce.