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.
So kilometre means 1000 metres, and a kilogram is 1000 grams. Similarly, the prefix âmilliâ means âdivided by one thousandâ. So millilitre means 0.001 (one thousandth or 1/1000) of a litre, and a milligram is 0.001 (one thousandth or 1/1000) of a gram.