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.
Gram (g) is a unit of Weight used in Metric system. Megagram (megagram) is a unit of Weight used in Metric system. Grams also can be marked as grammes (alternative British English spelling in UK). Megagrams also can be marked as Mg and Megagrammes (alternative British English spelling in UK).